Edit: It took me awhile to write this, since then people have chimed in that your lens is EOS not FD. That changes the body recommendation, but not much else.
I was just photographing rings last night. I used a foldio light tent, an AE-1, and a Canon FD 100mm F4.
I'm not sure who disuaded you from the 100mm, but I prefer it to the 50mm Macros (I have one of those on my Olympus 35mm kit) for small stuff. It has a smallish minimum focus distance. It is much closer than the zoom 70-210 Macro I have. The 70-200 zoom is definitely hard to use for small stuff.
On the 100mm, the ring ends up taking up the middle 1/4 or 1/3 of the image at minimum focus distance. Depending on vibration in the camera, and film used, I can probably blow that up to look OK taking up the majority of an 8x10 print. I'm not certain, I haven't tried yet.
I've got mine setup on a sturdy tripod, and I use the self-timer (the AE-1's electronic self time is fantastic btw, much better than some of the clockwork mechanical ones I've used recently - none I've delt with seemed to age well) to get vibration free shots. The AE-1 is also good because it can do 2 second exposures (most my other cameras only go up to 1 second). Definitely get an AE-1 (Progrma or not). The AT-1 has a less awesome light meter read-out (but otherwise is a fine choice - I have on sitting beside me on my desk right now), and the A-1 can't do full manual (Aperture Priority only I believe).
As for specific setting, that depends on how much light your light tent puts out. Mine, being a small little thing running off a 9v battery, does quite well at F8, 1 second, using ISO100 film. The light meter in the AE-1 is really good for this. Just put a gray card (if you don't have that, a light gray t-shirt) into your light tent where the jewelry will go. Set the film ISO on the camera to what you are using, and half press the shutter button. The light meter will read the suggest aperture value. F4 will probably have part of the ring out of focus (not sure with 50mm, definitely does with 100mm), F8 will have it all in focus. I'd aim for F5.6 or F8. Adjust your shutter speed until the light meter reads the aperture value you want. Set that aperture, pull out the t-shirt, put in your jewelry, refocus, and you're good to go.
As for what film to use, I highly suggest Delta 100. Since you have a light tent and can do long exposures, ISO 100 is a good choice, and the Delta films handle shiney metal in a very pleasing way. If you can't develop B&W film locally, just go with Ilford XP2, it's fantastic and gets developed as a colour (C41) film, so any film lab can do it. It is also very fine grained and handles highlight details (blow-outs) well.
Most film labs these days (every one in my town) offers scanning services when film is processed. If you use a mailer and send the film away to be processed, they will certainly offer scanning (check the APUG sponsors, I think there is at least one US based mail-order lab sponsoring APUG).
As tkimya said, there is a big difference in what you'll get enlarging the photo from the negative onto photopaper, vs what you'll see on the screen from a negative scan. Scans greatly increase grain, and limit the actual tonal range of the film (not to mention the limitations of your monitor). If the best image quality is your goal (say if you want to hang a photo in your studio), getting the negatives printed in a traditional dark room is defintiely the way to go (I've have a couple of negatives 'digitally enlarged' locally, and I've always been disappointed).
If your goal is just to post pictures to the web, getting a FD to micro four thrids adapter and picking up a cheap m43 digital camera (any Panasonic G, GF, or Olypmus PEN P, PM, PL) will be faster and much easier. That's outside the realm of this forum, so I won't go into it further; but it is a faster way to get your photos on the web, and has similar quality to scanned negatives.
Edit: Since it is an EOS lens, just buy an old Digital Rebel. Anything made sicne 2008 will be just fine for posting to the web.
Lastly, have fun!