1) http://www.pumpingmoms.org/
An incredible, invaluable resource for you, whether you're pumping just until you get your son back to the breast, or whether you're pumping exclusively and feeding breastmilk via bottle. Amazing support from other moms who have been there. Run, don't walk, and join that group. High volume, but truly amazing resource. http://health.groups.yahoo.com/group/pumpmoms/
2) Your mileage may vary since your baby is his own unique person, but my little guy has never taken more than 4-6 oz of breastmilk per feeding. When he was a newborn, 3-5 ounces was it. And at 10 months when I gave him a bottle (we had a wedding to attend), it was the same deal, no more than 5 oz. I'd say just experiment if you're concerned at all with his intake --> if you think it's not enough, add another .5 or 1 oz, and if he finishes it, ok. Plus, don't forget that they sometimes cluster feed - perhaps then he'll want more oz than he typically goes for, but then that next feeding may be a small one (just one example of why they might vary their intake).
3) About the pumping, Michelle, we were in the same boat! I had to pump for my little guy for the first 5 weeks, and while getting him back to the breast was a feat (my gawd, that was difficult - we had to ditch the bottle and use a freakin' cup before he'd cave and latch on to my breast!), I'm so SO glad & grateful that we pushed through that incredibly exhausting and difficult time because IT DID PASS. I could hardly believe it myself. Seriously. I really thought I wouldn't be able to breastfeed my son - this coming from a mom whose oldest nursed for 2.5 yrs (and had a rough start that time, too). After weeks 6 & 7 passed (transitioning from bottle to cup to breast), nursing actually became bliss, easy, natural. It felt so long when we were in the rough first weeks, but now my son is 12 months old and those 5 weeks of pumping, hard work, exhaustion, and frustration are just a drop in the bucket, a tiny blip on the radar, compared to the last 10.5 months of simple, easy, 2nd nature, skin-to-skin breastfeeding. So hang in there if you can. :)
4) Also, a few other things: you can pump exclusively if you have a hospital grade pump. If you are not planning to put him back to the breast but do want to continue to feed him with your breastmilk, get yourself ASAP a *hospital grade pump* - period. Even these are cheaper than what formula would cost you, and you get all of the added benefits of breastfeeding (reduced cancer risk for mother, reduced diabetes risk for mother AND child, fewer illnesses & less severe illnesses for your child, and that's just the beginning). Just make sure you have the right pump and surround yourself with support!
Best of luck to you - and CONGRATULATIONS on the birth of your son!