Can you do everything without a power button?

my power/sleep button recently broke (or got stuck?) either way, my phone that I never once dropped or has no scratches at all no longer has a functional power button.

is there anything you can't do without it? I know you can do the following in other ways.

screenshots/sleep/shutdown=assistive touch
Booting (from shutdown)=plugging into charger (will automatically boot it)

what if my phone freezes? I don't think there is a way to get it to hard reset, would I just let my battery die?

also what if an update goes haywire and I need to access DFU mode? am i screwed?

anything else i'm missing?

I already looked into that

it is a 4S and I have plans to get a 6, I just want to make sure nothing screws my phone up in the next couple of months

I think something like tiny umbrella can put it in dfu mode right?