Half your gear is dps stuff and its all pretty low itemlevel so no you're not ready to tank anything except normal dungeons. If I were you I would collect some justice points and 333 gear in normal dungeons then get into heroics and then get into ZA/ZG.
Alternatively you could also get some boe gear, valorpoint bracers must be pretty cheap at this point, 359 boots are really cheap, there are shoulders from BoT, thrall questline gives a 365 cloak mantle of patience, can do Tol Barad dailies for the mastery trinket etc...
If you aren't currently aware, your sword is somewhat on the useless side. I would replace it with any 333 that has Stremgth or Mastery, if you get something better than than that, Kudos to you.
Stamina trinkets are next to worthless UNLESS you are CTC capped at this point in the expansion.
Using DPS gear is ok, IF you reforge it. Your stat priorities go as follows: Mastery > Dodge=Parry > anything else. Basically, your rule of thumb is: If it does not have Mastery, make it have Mastery. If it has Mastery, reforge the other stat in a way that will achieve Dodge=Parry. Initially you will be reforging into Dodge a lot to overcome the amount of parry you gain from Str.
Threat: You do not NEED hit or expertise. Threat has received a number of buffs throughout the expansion and is going to get buffed to a point of retardedly easy when 4.3 hits. I'm talking aggro with auto attacks easy. For the time being though, you are going to run into problems. I say this because you are under-geared. You will need to be exceedingly proficient at your rotation to maintain threat against DPS who out-gear you by any more than a few ILvL's. This does not necessarily mean you are bad if you lose threat, quite simply tanks were not designed to keep threat against dps that greatly out-gear them.
You're a JC with an empty gem socket? As soon as you can get your JC gems in you gear. For tanking you're only going to need 5 gem recipes for the time being.
Yellow (Yellow/Prismatic sockets)= Fractured Amberjewel/Chimeras Eye x3
Orange (red sockets)= Fine Ember Topaz
Green (blue sockets)= Puissant Dream Emerald
Meta (Meta Head slot)= Eternal Shadowspirit Diamond