Some Questions from a Lowbie TankFollow

So I have decided to get into instances (Scarlet Monastery) with my druid. Of course, I am mainly looking to tank, but will fill whatever role the group needs. However I do have a few questions. My spec atm is a cookie-cutter Feral with the Omen of Clarity, minus a bunch of talents cuz I am only in the late thirties. I'd like to think I mostly have a handle on things when a pull goes well, my questions are mostly about when it does go wrong...

1. What should I do about casters? I remember doing SM with my Warlock, and allot of tanks straight up ignored them (and I would usually open up on them because they would often go for the healer). My problem with them is that they don't need to follow you around like the melee folks do. This becomes an issue if there are 2+ of them because I would need to run back and forth to make sure that I have enough threat on them to keep them on me. Should I suck it up and bounce between them? or is there something I could be doing to make life easier? I know it probably doesn't matter too much at SM (like I said, it happened allot with my lock), but I think it would be something I have to deal with eventually.

2. How do you deal with adds to an already large pull? There are two places in SM Library where you have a 3 mob pull, and a good likelihood of getting two adds mid battle. The problem is the never want to start beating on me, and go for two other people. I go into pull aggro, and usually lose one of other mobs I had. It usually not an issue of rage, but not being able to face all the mobs (and thus can't spam swipe). Any suggestions?

3. Why do so few people have Omen? Especially that guy who always pulls off you? Will this get better as people reach higher levels? (I kinda ignore Omen with my lock, since most tanks don't seem to have it yet in the low 50's).

Generally speaking healers are #1 candidate for CC beceause they can draw out a fight, and casters are next because they deal lots of damage and are a PITA to tank.

To add my $.02 to xschuhx's solid response:

1) When LoS pulling casters, explain to your party what you're doing and why. It takes longer to develop and any hit landed or healing done while you're trying to drag those casters around the corner blows the strategy out of the water.

2) The "magical pull" is just as effective, and more important, with cc-light parties where you're tanking more than 2 mobs and dps isn't cooperative. If you're having trouble grabbing aggro drop starfire on target #3 for max damage on the mob you won't get back to right away, moonfire on target #2 for instant cast damage, and then engage with target #1 to start layin down your threat-modified bear form melee damage. As with LoS pulling, party needs to know what's happening and lay off because you aren't building any threat on "first kill" mob until they get to you.

3) No Omen = /grumble-grumble. Lack thereof is a problem that persists to level 70 in PuGs in my experience. Only gets better when you're in a guild run where it is encouraged/enforced more formally. I hope Blizz incorporates a basic threatmeter into the game at some point. Apparently too many people find the extraction of a zip file into their WoW directory a great challenge, I guess.