Character/job level questions (spoilers)

So I went on a break after getting to this point in the game (spoilers) (SPOILER) My party got to the new continent and has their ship grounded by a golden chain

with my parties current character levels/job levels, am I in a good place? I heard when possible its best to grind job levels in ur on goblins.
also how long until I get the chance to go back to ur for this?

also for some reason my thief has the highest job level, i mean way past the others, and i just recently turned one into a knight, that makes sense for that character.
but my white mage and black mage have been that job ever since it was available

posting screenies of my characters status pages to help with this

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Once you reclaim the ship you can go back to Ur, it's in the southwest side of the map.

Using the actual job skills of the class will raise it's level faster so that may be why you're thief is higher in their class than others.

Levels don't look bad for that point in the game but I will warn you that FFIII does have a bad habit of having pretty sharp difficulty spikes but I think you should be fine for the moment. Also, make sure to switch your mage characters to Monk. Black Belt occasionally to get a level. Your HP growth is directly connected to your VIT stat and so if you level up with a class with high HP you get higher HP. It's the only stat actually affected by what class you are.

Now I'm playing on the PC/Steam version. How should I equip a monk for better effectiveness ? Also if i make both of my mages monks for a time, how am I supposed to keep my team alive? Do they get access to white magic?

It's a bit late, but, as I recall, Monks have no access to white magic, or magic of any kind really. There is always the option of potions if you need healing, but at the point you mentioned I don't think you'll be too bad off without white magic. Monks should deal enough damage to kill things off for you before they are much of a threat. Also, you can keep your eye on your xp and swap your mages to the monk class before you level. You'll lose your remaining spell charges, which is a headache, but it'll give you more max hp for the earlier sections of the game. Later on my experience with the remake is more limited, but in the NES game I swapped my mages to the Warlock/Magus class, which had better HP growth and still let me use black magic, for clearing mobs in the Bahamut cave for xp.

As for gearing out your monk better, just go bare fists after Nepto's shrine. You'll score a lot of hits and being unarmed always counts as having two weapons, so you'll get more damage too.

For leveling classes, some classes will gain job levels faster than others, and their progress is based on how many and what actions they completed in battle. Job specific commands, as Kanno mentioned, do give more class xp towards the next job level, but one can usually defend (or use another non-attacking option) ten-ish times in battle before ending it for a guaranteed job level. This rate falls off after a certain point, so you have to defend/idle more times, but the method will work until you max out the job level.

Hope that was helpful in at least some measure.

The Monk with/without weapons thing depends on the version. I tested this very studiously in the DS version, and past the very beginning of the game there are exceedingly few instances that it is favourable to not equip a weapon.

I don't know which mechanics are at play in the PC/Steam version, however I would think they would be the same as the DS.