On toxicity/dev run ins never had an issue. If you just play the game, don't be racist, sexist, create stupidly offensive character names, decide you must gob off in in-game chat etc then you will never have an issue. The ToS is pretty clear and not particularly onerous to abide by, just play the game and enjoy it for what it is then no issues i'm sure.
Progression is linked to gearing/levelling character and renown levels so its not a level playing field but I have no problem with more effort you put in better you potentially become, although skill does come into play of course. Levelled a few alts and its not particualrly hard to get them up to a decently competitive level in a few weeks. They won't be the best but decent enough to compete, especially if you group up in Warbands or guild parties. Also if you are sub 40, when in the rvr lakes you are bolstered to a level 48 character and while not geared your stats are boosted, so the game gives you a certain amount of hand holding to start off with,If you want instant equal playing field then no but I personally enjoy the progression. That said, apart from the rvr lakes, which are kind of the open world rvr areas, you can also do 24,12,6 man instanced pvp scenarios. Levels 1-39 have their own instancing so you won;t meet the uber geared players in there and a good way to learn and perfect your skills. There is a 6 man ranked scenario that is for the try hards

Population is good and goes up and down. EU primetime and weekends are the most popular and also depends on events occuring but you will always get a good fight.
Questing, handy for leveling your character level a bit but mostly 90% the time i've levelled them via pvp. There are 2 levelling mechanics in this game, character (1-40) for your core abilities and renown level (1-80) purely from pvp and add extra abilities above your character level. These are really used to let you build your character in a specific way.
I would just say defintely give it ago, its free so nothing to lose. If you want more info before jumping in LazyPeon did a good review on youtube and this weekend is the Twitchdrop event. |Zarbix,WarMaunz,Sweetumz, FixxerTv,ZappyTapp,Gravord are all good streamers to watch to get a feel for the action.