1, non-inverting amplifier with gain>1 or a buffer? it matters, and both are non-inverting amp.
2, probably an NMOS input stage can handle this, it is fine.
3, ok
4, this is an issue. your class AB architecture's max output voltage is ~ VDD-(|Vdsat.5|+Vgs.11), where |Vdsat.5|+Vgs.11=|Vdsat.5|+Vdsat.11+Vth.nmos < 0.3V.
I don't know 22nm technology, but with good ~0.1V |Vdsat| for both NMOS and PMOS the max. Vth.nmos should be 0.1V. It is too small, even with sub-threshold operation for the output stage.
Check the Vth of your devices, if those are higher than 0.1-0.2V I think you cannot ensure your specifications.
...minimum output voltage has the same issue, figure out why.