The A7

The iPhone 5s is the only product currently with the A7 in it. Simply put the A7 is a faster 64bit processor. What that does is let the phone load, render, etc quicker then the older A6.

The iPad 5 will have an A7X chip in it. And the iPad Mini 2 might also have an A7X chip in it.
As far as the iPhone 6, it's anyone's guess. But it will more then likely have a chip called the A8. Which will be a more powerful version of the A7.

 

I would say marginally faster boot time. iOS is designed so that rebooting your phone is a rare thing to do.

 

iPhone 6 will have the A8

 

Faster processors often meant faster iOS boot times, but I don't see it as an issue considering I have rebooted one of my devices maybe twice in the past month. Remember that the beta will not perform like the final version of iOS7, its most likely running a bunch of debug code at startup.

Do you really restart your iPad frequently enough to worry about the boot time?

The iPad 5 will probably have the A7 or A7X. The iPhone 6 may have it, or it may have the A8 processor.

 

I think Apple will keep the iPad Mini a generation behind the larger flagship iPad line - like what they did with the iPad 4 and iPad Mini 1 and what they are doing with the iPhone 5s and the iPhone 5c. So, I expect iPad 5 to have the 7x and the Mini 2 to have 6x.