buy a 'talent' and do 5 or 25 or 100 instantly.
but they should improve the talent for single chests yes.

go to the chest screen. click the bottom left thing. where it says idols/talents. and buy the one called speed looter

I'd still really like an open all option, or at least if the 100 button would open all your chests if you had less than 100. If you have 99 chests, you have to do the 25 button 3 times, the 5 button 4 times and then 4 individual chests.

ok, so 99 is a weird number, sure, but what about 20? That still takes 4 times the 5 button. It's not like we're talking about anything that could change the balance of the game at all. I think the only reason to not do this is because it will take time to implement that they might want to spend working on something else.

no, I envision it just an extension of the current open 5, 25, 100. where if you click 25 but only have anywhere from 6 to 25 all those will open. open as many as you have up to the 'size' of the button you clicked.
silver stays separate from other chests like they currently do. a button is for the kind of chest you are clicking the button for