Allow both faction and country specific units + Available turns 9 - ∞

I want to give Redcoats and Jaegars to Prussians and Brits but I also want slaves to be only buildable in Africa. Why not have an option in units screen?
Also very minor but why can't units be available from turn 3 up to forever?

It can just make it turn 3 to 500.

I can't go above 2 digit numbers.