[jimbob55]

To make mines less damaging, go into the Components.txt file and search for warhead. There are a series of values (100 0 0 0 0 etc) change that 100 to a lower value to get lower powered mines. Warhead 2 and 3 are just after that record, so mod them as well.

To change point defense + other weapons to sweep mines go into the components.txt file and search for the component you want to add minesweeping ability to and do this:
Change the value after Number of Abilities := ... to one more than it already is.
add :-
Ability 1 Type := Mine Sweeping
Ability 1 Descr := Can sweep 1 mine per use.
Ability 1 Val 1 := 1
Ability 1 Val 2 := 0

This section to the weapon's data BEFORE the Weapon Type entry. Having looked at a few weapons, they mostly don't have abilities other than their weapon type.
The Ability Type is the special thingy you are adding to the weapon (there is a list of valid types at the top of the comps file).
The Ability Descr is what appears on the component description picture. The Ability value is the level of effect of the ability (in this case the weapon will sweep 1 mine)

Assigning a maximum number of mines / sector would require some hard coding (I think), or at least I don't know how to do it.

I think a minefield will attack one ship repeatedly until it is dead. The ship's shields and armour (if organic) recharge between hits.

The mod that makes PD cannon sweepers as well is good, it makes mines pretty useless though because the AI is modded to mount 20% or so PD cannon on every ship. You need a minefield of over 100 to kill each ship pretty much... Mines are more expensive to produce making them even more useless.