1. If your goal is "get aggro!" or "oh god this enemy is killing me I need Defiance", then Unchained remains a good idea. Discarding it completely because of Fell Cleave is not a good idea, especially before you're Level 60 with some gear. As for rotations to maximize damage, an Unchained rotation remains the same. Get a double Inner Beast in there and call it a day. For Deliverance rotations, it's all about fitting 3 Fell Cleaves in a Berserk. If you use both Vengeance and Raw Intuition(Level 56 Skill) to give stacks during the window, you can also easily fit a fully powered Fracture into Berserk with those 3 Fell Cleaves... but keep an eye on your Storm's Eye timer. Doing too many actions outside of combos will cause it to fall off. Use it twice in a row whenever you think it'll fall off.

2. The usual Cross Class skills are as follows:

Provoke
Convalescence
Internal Release
Awareness
Flash OR Second Wind

Mix that last slot up with whatever feels like it will be most useful in the current situation.

3. At level 58, you get a skill called Equilibrium. If used in Defiance, it is a very potent Self Heal. If used in Deliverance, it restores 200 TP. It is on a 60 second timer. This should prevent all TP problems forever

And, regarding that video Freyyy is pushing down your throat... be wary of it. While I'm sure Mr. Vex means well, his videos are absurdly easy to misinterpret to the point that most people who watch them come out them worse at Tanking than when they began.