The buttpad was standard issue with my gun. I lucked out and never had to do anything with it. A good buddy of mine recently purchased his own Shadow and it being a 2006 manufactured one, had a different buttpad with less recoil holes but also they were larger.
As near as I am able to tell my bipod does not adversely effect my accuracy. I have shot the gun without it and have found I do better WITH it thus, it's on the gun most of the time.
It is a Leapers bipod that I got from Leapers but there is a bit of a story behind it. I had originally bought a very similar model through cheaperthandirt.com for $20. I had about 1200 rounds through my gun with it on there when the bipod broke at the point where the top of the clamp meets the bottom of the base. I called Leapers and talked to a fella there. Once he understood what had happened and where the break was he went and did some research with a feeling that the one that I'd purchased was not right for my needs. A half hour later he called back and said that after talking to the engineering dept. he had determined that for my style of shooting I'd be better off with a slightly different model. I sent them back the old broken one and they sent me the newer model at no cost. It's held up ever since. I've recently seen the newer one in my latest cheaperthandirt catalogue here:
http://www.cheaperthandirt.com/BIPOD103-41834-724.htmlIt's very easy to put on and take off, fits a good range of barrel diameters and in my opinion, really helps me get the shots off. I am currently able to hit knickles at 30 yards. The only negative thing I can say is that after a few rounds out of the Shadow it seems to loosen up a bit. I know I could fix that with some blue locktite but I prefer to have easier removal if so desired. Therefore, after about 20 rounds or so I usually just tighten it up again. It's hand tightened so it takes no more than 1/4 turn and it's back to normal.
Hope this helps.