Let me try to answer your questions in order...

1. RAW files have an extremely small thumbnail embedded in them that is absolutely useless for checking focus, etc. If you want to do a quick preview, it is much more convenient to open up the JPEG to quickly see if a shot is worth putting through RAW conversion or not. Small/fine is more than sufficient for this purpose.

2. I haven't shot time exposures with film, but I recommend using the noise reduction feature. The results are worth the extra time. I just leave it on; it is only used on exposures > 1 second or so.

3. No opinion, I havent done a serious film/digital comparison, but shooting ISO 400 is less noisy than underexposed ISO 200 and adjusting exposure in the RAW converter after the fact. In general, film is much grainier than digital for identical ISO.

4. Auto white balance will get you spot-on results about 90% of the time, and it will be fairly close the other 10%. The main trouble situations are where there are multiple light sources with different characteristics--a room lit with fluorescent lights with an open window allowing lots of sunlight in, late afternooon outdoor shots with mixtures of shade and direct sun, etc. Generally in these situations you would want to open the file twice, apply different color settings for each kind of lighting, and blend the results together--no one color setting is really appropriate for the entire image.

5. I use Adobe RGB; this setting only applies to in-camera JPEGS, so if shooting RAW it is irrelevant.

6. Sharpness is also only applicable to in-camera JPEGs. Shoot RAW, and you can sharpen however you want.

7. Get the 1 GB Microdrives; they are currently $176 each on Apricorn's site. I have 4 drives from them, so far, no problems. Microdrives have a faster data transfer rate than CF cards, but they have a 1-second spin-up delay. So they start transferring data 1 second after the CF card, but quickly make up for lost time. The buffer on the 1Ds is big enough thet the 1 second spinup delay is not an issue.

8. The manual says the screen can be changed, but I haven't tried to, so I have no idea what the risks/benefits are.

Oh, by the way, examples of a couple of my recent photos using ISO 1250 with 5-minute and 2-minute exposures may be seen here:
http://www.geocities.com/samirkharusi/alamayn.html
I do not think I ever obtained such clean images with my earlier use of Fuji ISO 800 color print film. Now that my long exposure needs have been met by a 1Ds, I can't think of any use for film.

Thanks again to all for your excellent answers -- and for helping me out.

Now I have a more frustrating problem -- with the Epson 2200 and their so-called professional RIP driver.  I'll post that in the appropriate forum -- if any of you can check that out it would again be greatly appreciated!

I just placed an order for a 1Ds to replace my 1V -- I'm making the plunge to digital.  I've read all of the articles on the web site, but have a few questions -- which will also help me to decide if I need to keep a film camera for some of the below situations.  

Please accept my sincere thanks in advance to anyone who responds to my questions.

(I'd recommend that Michael consider posting a tutorial with his own recommendations for how he uses the settings on the 1D or 1Ds -- it would be very useful for someone just starting out with the cameras.)

(1)  In his reviews of the various DSLRs, Michael stated that he shoots using a combination of RAW and small fine JPEG.  But he doesn't explain why he doubles up and shoots both.  In light of the fact that any large prints will be made from the RAW file, why does he also make a JPEG file that only adds to the file sizes?  What does he use the JPEG for?  And why that specific JPEG -- small fine?

(2)  When shooting longer time exposures (one second to fifteen seconds) at ISOs in the range of 100 to 400 -- how does the 1Ds compare to 35 mm Velvia or Provia film with regard to grain/sharpness versus noise/sharpness?

For example, if shooting in a dark canyon late in the day at five to ten seconds, would you recommend also applying the noise reduction that doubles the processing time?

(3)  How does the 1Ds at ISO 800 or 1200 compare with 35 mm Provia 400 film that is pushed one or two stops?

(4)  Would you recommend just using the auto while balance setting, or would you switch it based upon the conditions (daylight versus overcast, etc)?

(5)  Any recommendation as to which color space you'd use and why?  Is it true that Canon optimized the 1Ds for color matrix 1 sRGB -- and is that the color space to be used for printing to an Epson 2200?

How does the normal sRGB compare to the normal Adobe RGB?

What about the vivid setting -- is it really the equivalent of Velvia or the saturated Kodak films?

(6)  For landscape photos, would you use any of the sharpness settings as a default setting to apply to all photos?  Any advantage to applying a modest amount of sharpening to the RAW image at the very start?  Any disadvantage?  What setting would you recommend?

(7)  Compactflash cards -- is there much of a differnce between those at 20x versus 32x versus 40x?  Can the 1Ds take advantage of that increase in speed?

(8)  I could never quite understand why Canon didn't use the EOS 3 Ec-N brighter screen at the factory installed screen.  It might have a little less detail but is clearly brighter.  Ditto in the case of the 1Ds -- or so I assume.  Any downside with the digital SLR in changing the screen?

Thanks again for your response.

Marty, you'll very quickly find your own mode of working :-)  I think what size Jpeg you take with your RAW depends on what reject ratio you anticipate. For astrophotos I may reject as much as 90%, so I use the highest quality jpeg to go with my RAWs. That way I can examine focus and tracking at 1:1 without having converted any RAWs. The cost is next to nil, just a few extra megabytes along the way. But be prepared for the megabytes! Incredible how a GB suddenly becomes so puny. Those 65 MB tiffs (@16 bits) really fill up your storage quickly. I use Breezebrowser for my deletions, since it very conveniently deletes the jpeg, raw and thumbnail all in one go.
White Balance, High/Low Chroma, Sharpening, Noise Reduction: Frankly once you shoot RAW the choices are so many that it can even get in the way. For me (probably for most) these are all decisions for the PC stage. It's quite interesting to use the different White Balance and Chroma settings to view, say, a sunset scene in your RAW converter, and you can still vary the color temperature... Decisions, decisions.
High ISO compared to film: No comparison, the 1Ds outperforms film very substantially, I would say all the way out to several minutes' exposure at ISO 800. One could conceive that film might be better at, say, half hour+ exposures at ISO 800, but again, reciprocity failure would probably make that equivalent to only a 10 to 15 minute exposure in a 1Ds. I never really understood why there's an option for turning off that long-exposure-noise-reduction function. In a 1Ds it does not stop you from taking more photos while it's processing. If, say, you take 20 images each 3 minutes long, one after the other, like I sometimes do, then all that happens is that at the end of your sequence the camera keeps on processing for a loooong time and the write-light for the CF card stays alight. Didn't check how long. I had used that programmable remote to take the 20 pics and I had gone to bed... But you can still take more pictures. At low ISOs the 1Ds is simply far, far superior to film, probably to well in excess of a half hour exposure at ISO 100.
Changing viewing screens: no problem at all. You even still see all the focus points no matter what screen you use.

WOW!! You have some excellent astronomical photos, even with film! I'm sure now however, that you'll enjoy it even more with your 1Ds. This reminds me of a program I saw yesterday on the History Channel. Some guy,(forgot his name, but you might know him)has his own home observatory that's probably better then many universities and he has made some significant discoveries and contributions to the scientific community.

He has a telescope that looks to be between 2 & 3 feet wide and all the latest sophisticated equipment that keeps the telescope aligned with the stars he's viewing throughout the entire night with the utmost accuracy. He takes hi-res photos with it also. It's in one of those large dome type structures, but on his own property.