Yes, Apply should buy back more of their stock, because that would keep the company strong and stable. The world is watching to see if Apple can stay competitive. Buying stock would send a good sign to the world, and it would keep the company solvent and strong. It would be a sound business policy.
Nope. I can't think of any reason that would require Apple to buy back more of their stock. They seem to be doing fairly good in the market as it is, and unless they're planning on taking the company mostly private, it wouldn't help. But Apple often acts without logic, so who knows.
The only reason to ever buy back your stock is if investors want to go in a wildly different direction than the company they have invested in. In this case it makes sense for a company to buy back control. Apple, however, is a company that pretty much gives the people exactly what they want, so the move would be a waste.
Apple's choice to buy back more of their own stock was a strange move, even given their literally 100s of billions of dollars in cash reserves. It was all done at the behest of Icahn who, though calling himself an 'activist', is really more a rich annoyance, a vestige of Milken's junk bond machine in the 80s.
Apple should not buy back more of their stock. I just think with all the talks that was going on that they would have already made a decision about this by now. Recently, their investors have backed out of more talks trying to press Apple to buy back more stocks.