The easy one first, 5th is spelt fifth

Marines are in effect movable, when you sell a ship that is marined a significant (I'm not sure if 100%) of the cost of the marines is returned to you allowing you to reinvest this in marines for the newer ship. Most people have a line of battle between 3 and 5 ships deep. When they buy a new lead then they sell the tail ship.
When you loose marines to attacks by other players they are automatically resupplied as long as you have credits available, in effect this acts as a ready reserve.
Not sure about the escape pod idea, knowing some of the people that play this game they would capture and enslave anyone in an escape pod

The shield abs % also act as personal shields for marines so this can be increased using commander points.
I can't say I like the idea of a ship anti marine weapon, you have one already and it is called your marines.