Within a single turn, one Focus token could be used to activate the Blaster Turret then another Focus token could be used to modify the attack dice ... correct ?

Correct.

and if you had the moldy crow upgrade you keep unspent focus tokens so in a round if using kyle katarn you could pass a focus to a ship in range 3, use 1 to fire your blaster turret,then use one to change focus into hit and then use another 1 or 2 to modify your defence dice,

Thanks for the replies.