(1) No, not necessary. Daniel Boone found his way across the mountains without any ACA maps. You can get state road maps (which I recommend in any event), and make do with only those. But they're very useful.
(2) Check the for-sale ads on crazyguyonabike. Some usually go up late summer through early spring -- you may be too late for this year.
(4) I expect you'll find the paper copies worth every penny they cost.
If you're camping, knowing where to look for good places to stay will pay for themselves a couple of times every $12 map.
If you're credit-card touring, you can try a combination of GPS (with motels and restaurants) and cell phone, but knowing there's a cheap motel in this town, or no re-supply in that hamlet, is worth the price of the maps.
As I mention above, you could make a route with nothing more than state highway maps, if you don't mind a few 20-mile stretches of busy highway and no shoulder, or running down a long gravel road to find there's no bridge and an impassable river (as the thunderstorm is coming and the sun's going down -- cue the coyotes!).