What accessories/weapons/armor should I bring with me for companions in Awakening?

There's a huge variety of good equipment in DA:O; it'd take a lot of time to list it all. However, if i were you-- i'd look out for the accessories Spellward, Andruil's blessing and Key to the City aswell as the armor you get from Wade in Denerim; both the dragonbone plate stuff and Evon the Great's plate armor. You don't really have to worry about gear from Origins though; you'll quickly get far better equipment.

Compare the stark contrast between Red Steel and Dragonbone to see how much better the gear in Awakening is. You could bring gear from origins that you find useful-- but you'll be fine either way. It'll only affect the early part of awakening, then mostly fade away as you get better gear.

Good luck with Awakening!