Corvette specials are for all intents and purposes the corvette’s weapon, so yes they take an activation to use, and can only be used once per corvette per turn.

Yes, all special abilities are mandatory unless the wording specifies otherwise (e.g. the Warp Beacon says ‘up to’). This applies to the flak cannon, but also any weapon effects e.g. in the event of friendly fire during a 2v2 game you must apply the weapon special effects to your ally.

No, when a corvette crashes into a capital ship it is destroyed and deals no damage to the Capital Ship

Every player starts the game with a full set of 8 command cards in thier hand, one of each type.

When boosting the accuracy of a corvette or PD module, the boost lasts for ONLY that attack. e.g. if your PD has accuracy = 2 you can spend 1 targetting token to attack with 2 accuracy or 2 tokens to attack with 3 accuracy. The next time you use the PD, the same applies; spend 1 token for 2 accuracy or 2 tokens for 3.