I am curious about the same sort of info. I gave my friend $90 to get me some shrooms, and I should be getting them later this week.
A really good source of info can be found here:
Shroomery - Experience Mushrooms
On there, is a list of frequently asked questions, how to avoid a bad trip, how hallucinogenic drugs work, etc.
I would say on average most people eat between 1-3.5 grams of shrooms. That's usually about 1-4 mushroom caps. Anything less than 1 gram and you probably won't feel much, and anything more and it will probably be too much for a newb mushroom user like me or you. Whatever you do, don't drink while taking mushrooms. And certainly don't drive. And make sure you don't have to do anything for the rest of the day before you take them!