Re: AR10 vs 700
OK, here's a serious answer. First off, any weapon you have can be used for the SHTF scenarios, but really those situations are just delusions from watching too many movies. Mentioning SHTF turns a lot of members off from answering your questions, so it's usually best to just keep those thoughts to yourself.
Zombies? Dude, I hope you're just joking but if not you really need to put down the remote and rejoin reality.
As for the weapon choice. You want it for long range target shooting. No brainer, get the bolt action. By asking this question I'm pretty sure your shooting and marksmanship experience are at the lower end of the spectrum. A bolt action is much easier to develop the fundamentals on over a semi auto. Master the basics, then move on to the higher skill levels.
For the followup shots, with practice you can manipulate the bolt on a Rem 700 very fast. Four shot 100yd dot drills in the sub eight second category are the norm for shooters who practice, and I've seen it down as low as six seconds from an expert lefty on a right hand bolt, all hits on 1.5moa dots. The semi autos don't bring a serious followup advantage until you're rolling CQB distances or multiple targets requiring a higher mag capacity than ten rounds when racing a clock. Everything else comes down to recoil management to stay on target for that next shot.