I wouldn't worry too much about LFR and other gear grind mechanics. The quests in the new zones will give you equal or better gear anyway. That being said if you just want to do it for the experience, go ahead and have fun.
If you can't select a 'higher' LFR you'll have to do them in order to unlock the next one. Can't say this for certain since I steered clear of LFR for some time now. If you know some people I'd advice to do Flex instead. Even if you know no one, a Flex run with strangers might be preferable to LFR.
A good thing to do would be to check out how your class(es) play after the talent overhaul and just enjoy the game. Also, if this is your thing, be sure to pick up the pets, mounts and achievements the various events now and in the next weeks are offering (pre-expansion event, 10th anniversary, Halloween event).