Ok, lets say turr has PTL and you use boost and barrel roll in the action phase......can you perform another of either of these actions since it would be free?

Or does the rule book trump this and no second use of either action?

Thanks again

You can only perform a given action once per turn. So far there is nothing in the game that provides an exception to this. Free actions just let you perform an action in addition to the 1 per turn limit that normally applies, neither PtL nor any pilot special abilities allow you to bypass any other restrictions on action use.

Turr + PTL works thusly:

Option 1: Turr does 2 actions in his main action step

Turr is stressed during combat, and does not get to perform any free actions

Option 2: Turr does a single action in his main action step

Turr can boost or barrel-roll after shooting, and stress himself to perform an additional action after shooting.

Option 3: Turr boosts/barrel-rolls during his main action step, and does the other thanks to a Squad Leader

Even though Turr is not stressed, he cannot perform the same action twice in one round, so he doesn't get to use his ability. As such, he doesn't get to activate PTL, and ought to have done so when he got that Squad Leader action earlier.

Option 4: Turr loses his action due to a collision, but enters combat unstressed

Assuming Turr has a shot, he is still allowed his free Boost or Barrel-Roll, and can stress himself to perform an additional action after shooting.

Option 5: Turr gets boxed in, and cannot complete a Boost or Barrel-Roll action

Being unable to boost or barrel-roll, this plays out similarly to Option 3.

For the record, Option 2 is by far the most common.
He can also use his in-combat attack action to do most of the B-Wing's Advanced-Sensors tricks (like Barrel-Rolling away from collisions or off of ninja'd Prox Mines).

In short: Turr is an awesome pilot!