I have only recently got back in to it myself with trying to get levelled up ready for Rise of Iron in September. Weapons wise I am out of the loop on which are the best or what rolls you want. However Nirwens Mercy is apparently good though I don't know if you can god rolls on it anymore. Outside of that, PvP weapons of choice seems to be pulse rifles or scout rifles - red death, bad juju or MIDA seem to be weapons of choice. Though I was having some good games last night with the raid scout.
They brought back Prison of Elders with Challenge of Elders, basically you pick up a ticket up from Variks and it is a score based system with bonus points for certain kills (this week is melee). Complete the challenges for score which sometimes can be done in 2 runs but sometimes needs a third speed run just to kill the bosses. Once complete you hand it back to Variks and get a guaranteed armour drop and weapon drop that is up to 5 light levels above your current level.
The raid is the same it was though they have added a challenge mode which changes bosses each week. Warpriest challenge is easy, Oryx is alright, Golgoroth is apparently hard. Completing challenge mode gives you an extra drop, an emblem and a fragment. Normal now drops up to 320 I believe and Hard up to 335 and, similar to CoE, drops are guaranteed to be up to 5 light levels above.
NF is the same and IB is the same but again if you get drops at the end then they are also guaranteed to be up to 5 light above. Drops from strikes and normal engrams are as random as ever but overall it is much easier to level up. In 2 weeks of doing HM raid, CoE and NF I got my warlock from 317 - 330 and just IB last night I got up to 332.