I have worked with Brute Forcing, Smurfing, Teardrops, SYN-ACK attacks, UDP floods and a lot more.
I'm sure that I can work with you to bring your site up to par. I can't promise to get rid of all attacks, given that such a thing is impossible, but I can really help you beat the majority of them.
I have worked for fansites, consulting agencies and research organizations so I have a lot of experience in ensuring high security (You'd be amazed what 12 year olds do if they get banned!)
As for identifying the attacker, I am pretty sure I can do that.