Re: PlO hi, I am new at Omaha so I was wondering if the board if paired is it safe to always assume someone has a full house?
What do you do if you have the nut flush or straight and there's a lot of action in front of you?

Depends on a lot of things, especially how many in the pot
and the action on previous rounds, etc, but it's pretty safe to
assume on just about any paired board with 3-4-5 or more players
your nut flush or straight belongs in the muck, unless you have
some re-draws to hit a higher full house and are getting the
right price (check, prefereably...lol) to take a look at another card

Yes, it's always safe to assume that. If there's a lot of action, you definitely want to dump anything less than a full house. As always, the more players the more likely it is.

I'll assume you're more of a hold-em player, since that's what everybody seems to be. In Omaha, multiply the number of opponents by 3 or 4 and play how you would in Hold-em. So, if you have 2 opponents, assume that's like having between 6 and 8 opponents in Hold-em. Act accordingly. The quality of the players doesn't change, though. If you're against 2 good players, ask yourself if you'd hold onto your hand against 8 good players with a lot of action in Hold-em.

Also new to PLO. Playing .50/.50 PL, most of the time the FH is there. Usually the big full, but almost always either that or the underfull. Keep in mind everybody has 6 hands, so the pair on board could be matched by a flopped set, or trips of the pair on board+ one hole card matched with another board card.
So, two players against you have a total of twelve possible hands, and especially if they stuck around to the river or turn before it paired they'll either tie you or beat you.
Also, if there's action when you have the nut flush, you can be pretty sure you are beat - almost no one plays non nut flushes aggressively, and almost no one plays straights aggressivley with a flush out there. Action if you have a straight usually means they can at least tie you + are drawing to the flush or FH.