Welcome to GBO!! You'll find the answers to all your questions in the FAQs and Help sticky, read thru em, you'll be glad you did.
You'll need a longer bolt for a laminated stock, bolt info is in the FAQs. All stocks are interchangable on H&R rifles and shotguns, forends vary a little, specially on the 10ga and 12ga slug gun.
The internals of the SB1 and SB2 frames are all the same, some triggers are great from the factory, others have a lot to be desired, triggers can be honed to just a few ounces if done carefully, but a very safe 2½-3lb trigger can be done yourself or by a competent gunsmith.
Tim