I am a bit confused on hiw exactly the "dont activate until you have the same ready deployment cards as your opponent" rule plays.

Say my oppoent HAS THE INITIATIVE TOKEN and he has 5 READY deploy cards at the start of a Round.

I have 8 READY deploy cards. Do i have to play my 3 cards first regardless of initiative if he choses so?

AND i come to the most important question : WHAT is the benefit of having More Activations than my opponenet (8 to 5) if i have to BURN the 3 more i have????

Yes. A player can choose to pass on his turn, if his opponent has more ready deployment cards.

The point of having a lot of activations, is that even though you might have to use a couple of them before your opponent makes his move, you WILL get the LAST activation in the round and that can be very important for some lists - ie. running Han up in position for his End-Of-Round shot etc.

The benefit is, that your opponent cannot pass, when he has the same amount of activations like you. So you have the last activation, if you have more activations.

There is no benefit in having 3 more activations than your opponent. It is absolutely enough, to have 1 more activation than your opponent. But as long as you don't know, how many activations your opponent will bring, 8 activations gives you a better chance to go last than 6 activations.