AoE Threat Priority:
Rend > Thunder Clap > Shockwave > Revenge
This is incredibly wrong - I understand the source is EJ, and believe me when I say I use EJ - but, initially, rend does absolutely nothing for you in the ways of agro.
The rotation should always be for AoE:
CS > Heroic Leap > Thunderclap > Shockwave > at this point, worry about getting a rend up and then thunderclap again for rolling rends. Tauren have a bit longer because we can stomp and stun the mobs for a bit longer.
Believe me when I say it will be much harder for your party to pull agro off after you HL > TC as an opener.
If you're doing normal 5-mans and having a hard time holding agro on trash pulls, the problem likely has very little to do with your gear. Your gear is going to influence your survivability, not your threat generation (blah, blah, hit/expertise, blah). Instead, it's going to come down to two types of mechanics: the mechanics of the pull and the mechanics of the rotation.
I can't really agree with this... I mean, you 'might' have a bit of a point, but it's a muted point. Just about 7 pieces of his gear has absolutely no tanking stats... instead, it has crit, expertise, or in the case of his second trinket: agility.
Before you start running heroics, if you're not carrying a lot of cash, spend a few days and finish up a bunch of the Cata zone quests - you'll find quite a few tanking pieces that will set you up nicely for 85 heroics. Also, quests can only help you to get the reputations you need for tanking enchants - they are a ton of reasons to do the quests, and very few reasons to not do them.