Say a ship has 2 proximity mines (or any action bomb). The ship does it's manuever and performs a proximity mine acion. If the ship is given an additional action (say via Squad Leader), can it then use another proximity mine? If not can it drop another action bomb?

Matt

No. A single ship can only drop one bomb (of any sort, manoeuvre or action) in a single turn.

Plus there's always the rule of not being able to perform the same action more than once in a round.

Nope.