Just made my first batch...

and I thought it was gonna be a piece of cake, but man, it's pretty easy to do something stupid. I was attempting to do Cheesefood's caramel cream ale, but I doubt that's how it's going to turn out.

I did a 2 gallon boil in a 3 gallon pot (no boil-over! ) It went well, but when the chilling was done, I got a little quick with pouring it and ended up transferring quite a bit of the trub into the carboy, along with some of the hops. I'm sure a lot of people have done this before, but is it a big deal? I think the extra hops in the carboy will just give a little bit of extra bitterness, but probably not what I want with this brew.

Anyway, I had fun and hopefully it will turn out well. I know, I know, RDWHAHB, but I can't help wondering...

Yep you got it, RDWHAHB. You can clean some of the trub and hops out if you decide to rack to secondary. I personally didn't care for the Caramel Cream Ale (too sweet for me), but I'm sure your first brew is just fine.

+1 on McBrew's response. I remember accidentally dumping a bunch of trub (and therefore hops) into an unhoppy style of beer. Didn't make a bit of difference. Since you're not boiling the hops you won't get extra bitterness - at most you'll get a sort of dryhopping effect (correct me if I'm wrong here). I'm sure it'll turn out great.

Well, after doing a bit of reading, there is one other (potentially big) mistake I think I made. After cooling the wort and dumping it into the carboy, I added tap water to fill to 5 gallons. Apparently I missed the part on boiling the water before putting it into the carboy, so did I put myself at risk for an infection with this?

I don't use boiled water, I use store bought bottled water. I think there are those that use tap.

As far as dumping trub into the fermenter I have heard this before and after doing 4 brews thus far haven't come across "trub" in my wort

My wort is usually clean and my last one had maybe 2 tablespoons of grain sediment at the bottom. Unless I've been dumping it in unknowingly, but I have never seen anything that didn't look like wort.