Popular questions that haven't been mentioned yet are
"Where do I put all these items/Is there a bank?" [Explaining about the armory, retainers, the chocobo saddlebag, the glamour dresser and so on]
related to that question is
"Do I have to keep all these things?" [Explaining about the part of the tooltip that tells you if an item can be bought at an NPC and for how much, also the calamity salvager and the other NPC whose english name escapes me at the moment]
other things my NN answers often are
"Do I have to do all the quests?" [Absolutely do MSQ (and how to tell what is part of the MSQ) and +Quests (except Relic quests you're not interested in at the moment); only do side quests if you're interested in the stories they tell]
"How do I change (back to) my class?" [brief explanation about changing weapons/tools, Job Crystals and setting up gear sets]
and
"I changed class, how do I catch my level back up to the MSQ?" [Giving a quick rundown of the Hunting Log, FATEs, Daily Roulettes and general leveling tips]
What doesn't get asked but deserves a shoutout is the Hall of the Novice, even if it's just for the gear it provides. A quick word about the <pos> command probably also goes a long way as that usually only gets brought up after some poor sprout asks for a rezz without providing a location.
More advanced questions that may not fall into the scope of your project but come up fairly often are
"Which crafting discipline should I get?" [All of them because recipe trees start interconnecting]
and
"Why does my GC not promote me to the next rank?" [In 8 of 10 cases because the squadron has been missed entirely or people missed the part about doing 5 different command missions; 1 of 10 each for missing completion of the GC Hunting Log and simply having arrived at the highest attainable rank]
edited to add: This usually only comes up after Auto-Translate has been used in the Novice Network but "What are those red/green brackets/arrows around words?" is another popular one and explaining about Auto-Translate is always welcome on servers that use a mix of languages for their chat, especially if people are asking for advice on abilities.