KK on board with 4-straight. Stupid bet?

[phuc]

I need some help on my thinking in this hand. Want to see if I should have played it differently.

Game is live $5/$10 NL with effective stacks of $850.

One early position limper (Villian). Villian is a fairly loose player who is in preflop 75% of the time and will call a raise on about 75% of those times (rough estimates, obviously). Postflop, he seems to pay people off if he thinks he has a chance to win, but doesn't always raise when he has the best hand.

I find K[img]/images/graemlins/heart.gif[/img]K[img]/images/graemlins/club.gif[/img] in late position and raise to $45. Everyone folds back to Villian who calls.

Flop is Q[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/spade.gif[/img] 8[img]/images/graemlins/club.gif[/img]. Villian checks to me. I bet $105. Villian quickly calls.

Turn is 6[img]/images/graemlins/spade.gif[/img]. Villian checks to me. I bet $200. Villian calls.

River is 5[img]/images/graemlins/diamond.gif[/img]. Villian checks to me. What's my play here? What are the hands that the Villian is likely to have?

I decided that he may have hit two pair or the straight, but it's most likely he was calling with the queen (something like KQ) so I decided to push it a bit and make a value bet on the river for $300. (note: villian only has $500 at this point and I'd probably be obligated to call if he pushes) Comments? How dumb was this bet?

EDIT: another note. my image is fairly tight and a solid player, but Villian is fairly new to the table and hasn't seen me play much. he's played plenty of hands (and my memory of his previous sessions) to give me a pretty decent idea of his play. Villian probably doesn't have any real impressions of my table image at this point (and may not really take it into account as much as a solid player would anyway)