ok, i re-read the rules several times, and i am still confused about this:
is there a limit too how many tactics cards you can use in a given turn of combat (i feel like it can be read as 1 or as many as you have)

So, my son and i are playing:

he attacks, and rolls his dice and gets 3 damage

i have 2 "block 1 damage" cards ~ am i allowed to play both then an save 2 of my 3 rebel troops?

then i roll and say get 4 damage: he has a "discard 1 card and block 2 damage" and a "block 1 damage" card ~ is he allowed to use both?

and related, when you discard a crossed lightsaber die roll and get a new tactic card, you can use that card immediately if it is a useable ability in the situation you are in?

Thanks!

There is no limit to how many tactics cards you play per round, and you may use them immediately after drawing them assuming you can use it.

No limit. Though often you have to spend a dice with the force symbol to play a tactic card.