Scope rings: Badger Ordnance... and Seekins looks pretty tough too... there are a handful of'em out there. You'll spend at least $100 plus on some decent ones.
Bipod: I've gone through 2 Harris bipods (sold'em)... and now I'm stuck with an Atlas bipod from Accu-shot and loving it! They're up there in price, but you'll only cry once about it

I believe getting an aftermarket stock/chassis will allow the barrel to free float. The difference between the two: with a stock you'll need to purchase the floor plate assembly if your looking to have a detachable mag set up (unless it already comes with it) and may require bedding. A chassis is already ready set up for that and you don't need to bed it... I think, mine isn't bedded on my AICS 1.5