First I dont want to be a comptive player which I call being WAAC jerk player.
But I trying to understand how and why combo's work and only why you can only use x combos.
Now with my list I dont see why I want to stress fel as I find stress not a good thing as limits what you can do
And I like abilities that add more attack dice as its hard to kill stuff
I'll echo some many of the others and say there is a huge difference between being a competitive and being a WAAC jerk. To be completely honest the WAAC jerk may not be the least bit competitive, although net-decking to find what should be competitive builds often helps terrible squad building, but has this attitude that is a pain to play against.
If you want to understand how/why combos work you need look no further than Fel and PtL. The Interceptor natively has four very good options when it comes to Actions but has the "problem" that you can only take one of those on any given turn. Where PtL combos well is that it then lets you take a SECOND Action. Because the TIE Interceptor has a lot of green maneuvers on its dial it is usually very easy to ditch that Stress. Maybe it makes your maneuvers a little more predictable but when you could use Boost and Barrel Roll to reposition after your maneuver it's harder for your opponent to capitalize on that predictability unless they actually manage to block you; if you do happen to get blocked you still lose the Stress and because you skip your Perform Action step probably aren't using PtL and gaining extra Stress so you've got a lot more options next turn. Now if you can see why Interceptors and the Stress inducing PtL often go together it should be easy to see why Fel fits into THAT combo so well as his ability gives you a token when gaining Stress.
If you are using Fel with PtL and getting a token stack but not using that stack of tokens then Fel is probably doing extremely well. In the full turtle mode he'd be getting an Evade and two Focus tokens. Depending on how many attacks he is going to face there is a high likelihood that one Focus may be used; statistically having dice modifiers with 3 dice is often as good as getting an extra die but no modifiers. With the Attack out of the way Fel can then use those other tokens to defend himself from attacks and if he doesn't use them all then either the dice completely failed you or you've already rolled well enough that you didn't need them this time.
Generally Stress should be seen as a bad thing to have. IF you are going for an Interceptor build that doesn't use Stress then giving up the point or two of PS and cost to use Turr or Jax instead of Fel as both of those have abilities that can be very useful.