So with the Space Marine list, there are two ways I can get Land Raiders on the table.

1) In a formation of 4 land raiders.

2) As an addition to another formation, and then only 1 at a time.

Problem.  If I buy them in a formation of four, the rules say a transport can ONLY transport units in the same formation.  So another formation of Terminators can't catch a ride?

If I buy a Land Raider as part of a formation of Terminators, I can only get one Land Raider maximum.  So not enough to transport all my Terminators.

What am I missing?

EDIT:  One more question.  Land Raiders have two weapons.  Lascannons and Bolters.  (AT and AP respectively)  Can they fire both, or is there a limit to how many weapons a single unit can fire in one turn?   (Searched for this, can't seem to find it anywhere, including the FAQ.  I'm assuming there is no limit, but I just want to make sure.)