returning/new player

You may have the answers to your questions already but in case not,
1 - yes they collect the level 100 materials. I had to redo my aa points to be able to get the goblin again. Just change your aa set up to get it to work again. Click build mode then commit to the build that has the goblin in tradeskill prestige.
2 - you don't get an item, you get a buff. You can hover over your icons in the spell effects window and see what it does. It provides multiple benefits.

With mercenary heal is not a problem (as tanking) - I am playing in ToT already and still running Kenny (elite mystic) work good