See, marines may not be allowed lances, but that doesnt mean they would be any worse than normal humans at space combat. It doesnt translate as well on the scale of massive space ships, and they do their best work on the ground, but each marine has an advanced and efficient mind. They are experts at every method of transportation and weapon under their command. Thus the +1 LD in space.
I think weapons should simul fire, but if so perhaps the entire fire sequence and who is fired apon should be declared before dice are rolled, for bfi purposes.
As to the old blast marker rules, I can see why they changed, but i can also see the blasts effecting that part of the ship.
If someone wants them to go back to the old way, I would definitly be interested in hearing the logic behind it, becaue it sounds doable.