The min and max you can play around it. the main thing is you don't want too slow that it affect your workflow.. if you want extreme, you can always try min0% - max10%
Normally min0% - max50% is fine for start, you can go lower slowly till you are happy.
Sleep is off cpu, off display but keep memory alive.. but during sleep, it doesn't check email, wake up from alarm, etc. But is instant on.. press button, its back as memory are still on.
InstantGo is like sleep, display off but memory and cpu still working at very low level, so backgound apps can still be running and wakeup on event just like a normal HP or tablet. also instant on.
Both Sleep and InstantGo will still go to Hibernation mode after a long(depends on settings) period of time.
Hibernation is off cpu, off display off memory, eveything off(zero power required), but before off, it dumps the whole memory content into the system disk( c: ) hiberfil.sys.
So when you press the button, it has to dump hiberfil.sys content back to memory. This takes a few secs(thanks to the fast SSD) but its still a few seconds of wait time before the system is back to where you were..unlike sleep and InstantGo where its instant on.
The one you are talking about the restart and load is not affected by InstantGo,
I believe you are referring to Fast Startup (hybrid boot). (this is dependent on the hibernation file instead.) disable InstantGo won't disable Fast Startup, but disable hibernation will disable fast startup.