just get a mechanical keyboard, cheapest will do. Rest doesn't matter.

I got a simple Sennheiser headset so can't help you there, just can tell you that I often don't hear
things :p. People swear at the logitech g35 though, never tested it, but it is expensive (100+ euros).

And they say that high DPI gives negative? (or positive, don't remember) acceleration.
But I tested it at various DPI levels, up to 5700 at different speeds, even tried the fastest I could do
and didn't notice the slightest acceleration. So I guess it is mouse dependent. I used the logitech g500.
Or the acceleration happens at speeds you wont reach with your arm+wrist or whatever, so it doesn't matter.