Never look at GS for tanks. Even for other classes it's bad. Discussing GS here is worse. That said, you're HP level is good for naxx or ulduar, possibly carried by an overgeared group through TOC10. Armory link would help. Otherwise, keep farming heroics, it's easy to get full t9 and some decent gear.
I think maybe I wasn't clear on WHY to go DPS. Of course tanking requires lots or practice and just mind numbing runs, but If, as a player, he wants to progress and he'll need to gain badges.
I did this by DPS'ing my way thru my daily ( 2 frost for the day ) then tanking 2 or 3 randoms ( still get triumph badges ). That way if I did have threat issues ( and was kicked ) i already had my FROST.
At a lower level gear, holding daily Heroic threat may be an issue, and he may get kicked from groups.
Also, if you're not familiar with the dungeon or the boss, DPS gives you a good chance to watch others tank and learn the ropes.
There are two ways to get more Frost without running ICC. Those are: running the weekly raid and running the most recent boss in VoA.
As far as raid requirements, it's a good idea to have upper-30k/lower-40k raid buffed health when running ToC10 or ToC25.
And as much hatred as everyone has for GearScore, it does give a fairly accurate layout of what level of gear you should have to run certain raids. You don't need to follow it down to the number, but it's great for ballpark estimates.
What randoms are you running without problem? All the way through H HoR? Its harder to find runs through anything below ToC so you might be better off upgrading your chest and belt, and then I think your more than good for ToC.
My suggestion in gear - The crafted 245 chest pieces have really dropped in prices, for 3k-4k (or less if a friend has the plan) they'll last you a long time (frost emblem pieces probably aren't viable until you start running ICC as just doing the daily would take 42.5 days for the chest). Plus this would free you up to upgrade your belt to frost first, which given your other gear would seem to give you the most bang for the buck.
Profession wise - BS/Mining/JC are roughly the same for a tank (+60ish sta). Personally I like Mining/JC - though I'm gimmping my DPS spec a little by losing the 2 gem slots from BS - but the benefits of mining/JC seem to fit together really well. At least pre-cataclysm, I think BS/Mining for a tank is a straight trade (60 sta to 60 sta) and Mining is slightly better in complementing JC (prospecting, especially when you get to titanium for gems and powder). Couple that with the decrease in non-icc crated gear prices and I think, right now, mining is > BS - that could change when Cata drops though. As I said - BS does have an additional tradeoff if your other spec is DPS.