Legacy of the Void

So lotv is coming out in a month (ish). I would advise you to play the beta until it comes out. Balance might be a tad screwey, but it's fun and balance isn't too important anyway (unless you're super concerned about you're ladder rank or if you're a pro player). If you didn't get a beta invite, you can get it immediately by pre-ordering lotv.

The current meta for zerg in legacy I think is mostly the same as in hots, but with lurkers late game (idk if they're used zvt, but definitely zvp and zvz) and ravagers to deal with liberators (and I think they're good in a bunch of other situations as well).

Because patches are still frequent, it's hard to give any definite advice. Mostly just have fun with the bizarre stuff for now and wait until it launches to try playing seriously is my advice.