Foxy,
To answer a couple of your questions, If you use a varmint taper barrel, you will have to find a stock off of a 12FV or use a B&C Duramax stock (around $100 for plain black). The big thing about replacing your stock is determining whether you have a stagger feed or a center feed. The easiest way to tell is when you take the stock off, if the magazine stays on the action it is a stagger feed. If it stays on the stock it is a centerfeed.
If it is a centerfeed, disregard the above about using a Duramax. They don't make them for the centerfeed yet.
I would say that a #4 taper is about as heavy as you can get by with using your standard stock.
I have not personally owned an A&B barrel, so I won't comment on them. McGowan offers prefit Savage barrels in whatever caliber and taper that you want for around $300 and they have great delivery time, about 4 weeks normally. I have one in 25-06AI and it shoots great. Pac Nor and Shilen both make prefit barrels in the same price range, but there lead times usually run 16-20 weeks.