Some clarification on Blue Mage

I'm still not entirely clear on what BLU brings to the table in this game, but I've read up on some of their skills like "white wind" and "lucid dreaming" and I'm curious of those abilities can be slotted in my action bar and used while playing as another class in PVE? are BLU abilities like the carryover abilities from the subclasses you would already have once acquired while leveling something like from a Lancer to Dragoon?

BLU is considered a 'limited job', meaning it's restricted from most other content above level 50 and from the duty finder. Their skills are specific only to BLU - you can't give them over to other classes or jobs, you can only use them as a BLU. Lucid Dreaming is an exception, as it's a role action available to all Caster DPS jobs (Red Mage, Black Mage, Summoner), which includes BLU.