You won't need a 20MOA rail for shooting at 100. When you're ready to his past 200, then it might be helpful. Scopes will depend on your budget. I like Vortex right now, but I've been reading bad things about their newer stuff lately. I also like Bushnell and Nikon for affordable glass. Check the optics section for info on optics. As for ammo, look for Eley, Lapua, RWS or even Wolf. It's not easy to find at the usual shops, but with a bit of searching, you can source them in Canada.
Having said all that, it seems to me you want to slap together another out-of-the-box rifle with decent optics for shooting top end ammo. I think you'd be better off looking at a higher end rifle is you want to get into some serious target shooting; but shooting at 100 yards with 22LR really doesn't require high end stuff. The most important question to answer here is one of budget. How much do you want to spend? That's ultimately what should dictate what to buy. Another Savage will do you well, if that's what you want. But if you want to get into some serious shooting, maybe consider Anschutz?
Again, it depends on your wants, needs and budget. We can give you all sorts of recommendations, but shooting high dollar ammo through an average rifle with a decent scope isn't going to make much of a difference at 100 yards.