I can tell you about the selection as I did it recently: it's a two day affair, Wizz will offer a free ride to Budapest and back on their network if you happen to have a connection, hotel is on you.
First day is company introduction, then the test (90 minutes, some maths question - no calculator, then ATPL, and if you're rated - some type related questions). After that there's a group CRM exercise with HR ladies watching you. Next there are two talks - one with pilots, one with HR - 30 mins each.
If you're lucky on the first day, in the evening they will invite you for the second day, which is FFS session. If you're non-rated - just basic handling skills and how quickly you will get used to FBW and sidestick. Takeoff, climbout, level-off, some basic manouvers and vectored ILS. If rated - they'll be looking for a bit more - maybe OEI action, some ECAM message etc.
As for when you're inside - all my friends who work there are happy, on paper looks better than RYR at least - proper contract, social security, some company benefits. Be careful about the base though - for FO's it's not a big problem, but if you're experienced the upgrade will come soon and waiting lists for Warsaw of Budapest for example are years long!