in regards to the mp issue, using potential/enlightenment runes solves that problem for short fights. As for longer fights, you can use some pots/food to help you out -- embrace of the muse and the crafted food that reduce mp cost as well as phirius potions go a long way.
As for pet skills, the return on damage per upgrade isn't great, but as peitroasp said already, lvl 50 costs very little. Upgrading punch on spirit of the oak is helpful too. With this in mind, keep all your passives upgraded as well, once they hit lvl 50 leave them there until your attack skills are maxed. Even with 250m tp on my warden I have yet to max Natural lifeline for example, but since upgrading it to lvl 50 doesn't cost much I have at least done that.
Max all skills that "cap" at 50, including the WARRIOR general ones -- I use berserk even when I am tanking. Keep double chop upgraded as well, it is actually the strongest hitting wd/w skill when both hits crit(when doing boss fights, the max hit of 1 double chop hit is more then half that of my max CC and it hits twice...).
Keep your other attack skills upgraded as well. As someone said before, your rotation for boss fights isn't CC, CC, CC, its CC, double chop, CC, beast chop/slash, CC, pulse master/slash, etc. because cc + 1 skill takes just over 1 second once you get used to doing it.
As for actual tanking/aggro skills, Double chop, beast chop, pulse mastery, frantic briar (when you have spirit of the oak out) all have 5x aggro multipliers, and Cross chop has 10x aggro multiplier (with spirit of the oak out). Regardless of whether you tank or dps, double chop is a must, but the others aren't high priority if you intend to play dps (though ofc upgrading them results in more damage output).