I'll gave it a try.
Is there some sort of .conf file when you can specify overclock settings under windows?
Is there some tweaks to have your gpu at 100% like in other mining coins?
I have 2 R9 290, what Hashrate should I expected, and where can I see it?
Overclocking is actually discouraged, as it tends to lead to small errors that can cause you to lose a work unit or have it "hang" near the end. Start with Stock clocks on everything.
I believe that the 290 does something like 150,000PPD plus, but I'm guessing a bit there.