you should've gotten two allen wrenches when you bought the guitar, a small one and a large one. use the small one, and adjust each string at the bridge via the allen screws in the saddles to what you like.
I really doubt that you have any loose frets, unless this is an old guitar and you play alot and might have cause some fret wear. You've two options. Shim the neck very slightly or have the frets leveled. the neck shimming is easy, just slip a folded peice of paper of something else very thin into the "neck" end of the neck pocket and tighten, but not too much. Your action should be raised. Or you can go for a fret level, but expect to loose fret hight and dish out about $75.
This is just a guess and there's no way to tell without handling the guitar, but the problem may be that the 5th string's fret slot is too low. Is it a plastic nut? Hopefully JohnJohn or one of the other luthiers will be along shortly.
oh yeah, I almost forgot. It's a strat, and you usually cant have a strat with light-ish (10's and below) strings and not have a little fret buzz. Now if its really bad and you cant clearly hear the note you're trying to produce, then you should take some action. But if its just metal on metal string buzz, then its something you'll have to live with. I wouldnt worry about it, it dosnt come through the amp anyway.
oh yeah, I almost forgot. It's a strat, and you usually cant have a strat with light-ish (10's and below) strings and not have a little fret buzz. Now if its really bad and you cant clearly hear the note you're trying to produce, then you should take some action. But if its just metal on metal string buzz, then its something you'll have to live with. I wouldnt worry about it, it dosnt come through the amp anyway.