Hey Jeremy,
(1) Proscar and finasteride are the same substance, finasteride. The only difference is the amount. Proscar is 5mg finasteride, and is used by men with enlarged prostates - they need a higher dose to shrink the prostate. Propecia is 1mg finasteride.
The folks on here taking Proscar are doing it because it's more cost-effective. Propecia's expensive because Merck figures its advertising and R&D costs into the price. Proscar's generic, so you can get more of it for less. Most people cut the 5mg Proscar pill into fourths or fifths, as taking 5mg finasteride per day for hair loss is not considered a good idea. Some doctors won't even prescribe it for hair loss.
(2) The studies I've read have said that there's not much of a difference between 0.2mg finasteride and 1mg finasteride. However, there's still a difference (0.2 inhibits about 20% less DHT, I think, although someone correct me if I'm wrong). I can't tell you exactly what this is because it varies from person to person - however, 0.2mg is as low as I've seen it used. I think a good course of action is to start with 1mg and only lower it if you get major side effects, but that's my own strategy.
(3) People have mentioned a couple of different sites. I don't have or know of any bad experiences with these sites, but I'm staying on the safe side - I use CVS.com. I figure the peace of mind I have from knowing I'm getting a legit product makes up for the money I might save if I got my meds from somebody's basement drug lab in Thailand
I recommend just getting a prescription and buying your meds from a major nationwide pharmacy.
(4) No problem! Good luck with your battle. As you've probably gathered from the commiserating on here, hair loss isn't exactly fun, but there are definitely options now and they're only going to get better. Fight this thing, wait it out, and if you're ever feeling down in the dumps, look up some posts by DarklyCharming in the Follicle Cloning forum. There's hope for the future.
- Dave