Welcome back.
1. You can access your Mog House's Sack/Satchel/Case anywhere. That's 100s of instant slots to use.
2. You can put unlimited number of items on the AH. Not 7 like retail. Just don't go to sales status.
3. Stay away from the giant winged Dragons that are randomly in the world. Those are OWNMs which are basically BCNMs but much harder, still level cap you and will kill you, they aggro on SIGHT. Most groups that kill them are gravity/bind/burn Mage groups.
4. Friend's List do not work, so create a Google doc to keep track of friends and also find a LS or 2. (Can equip 2)
5. There is a Chocobo Circuit which allows you to transfer from the main cities for 500 gil. Go from bastok to windy to sandy no problem.
6. Add Zeko to Google doc of friends list, that's me

60BST/37NIN/30WHM/30THF/18RDM/31BLM/5WAR
7. Nasomi has extended length of a monster being EP. You can get 30 exp from monsters much longer than retail and it is worth it for the extra crystals/quick exp when 2-3 shotting something depending on Job.
8. Some jobs have broken mechanics. Right now PuP is not that useful, and BLU has some physical Magic issues which they don't really become good until you can merit to fix some of the issues