Clicking thru the menu on the DR-05, I do not see any internal gain settings. The gain is set by the + and - buttons on the face of the unit. I have had no problems recording off a sound board.
The battery life is pretty good. Much, much, much better than the 2d.
Mine was something like $50 at a Black Friday sale. I see them for $79 every so often. I'd hate to pay $99, but I could see $50-$80.
edit: MF has it for $99, but has a $20.00 off sale right now that should bring it down to $79 with free shipping.