Something I found helpful to keep in mind when I was househunting: there are a gazillion houses out there for sale. If you absolutely LOVE the house and think it's just what you want right now, go ahead and make an offer for what you're willing to pay. If not, wait and look for others...I learned a -lot- just from shopping about what I should be looking for, what I wanted, what I didn't really care about, etc.

The realtor doesn't usually make the decision about which offer to take, the seller does. (But the realtor does make recommendations.) I don't know if they'll call you to let you know if other offers come in...they'll want you to bid your max to begin with, anyhow. But maybe. (It also might not be in your best interests; these folks work on commission, and I wouldn't put it past some of them to tell you other offers have come in when they really haven't.)

Hope that helps!