#1 There actually is a kind of save game already as the game remembers which girl & machine you used last. But of course it's completely without the current action. Still, I expect it shouldn't be too much work to additionally save the current stats of the girl, the status of the machine and which clothes were removed.
#2, #3 & #5 I expect that this takes a lot of effort to implement as the girls have to get way more active than they are now. Same goes for the clone.
#6 Would be nice but I expect that this will also be hard to implement. Simply tearing (or cutting) off light clothes like the underwear is one thing, but removing the armor would be... interesting to implement. Probably you'd have to add some mechanism that you can activate with your virtual hands.