Mines & Treaties

[Roanon]

I don't know about non-I and non-A as I haven't used them up to now. Resupply depots can be seen and used from Military Alliance upwards.

Your thoughts about mines are correct. Mines and ships hit each other and are used / damaged until either no mines or no ships are left. Compartment damage is remembered and carried over from one mine to next. Unspent mines or surviving ships remain.
Larger warheads give more explosive power to a minefield, but from a certain stage onwards no big fleet will travel without mine sweeper support, and they sweep the same number of units regardless of warhead size. So, basically, i consider large warheads as a waste of money.