Returning player asking for advice

Hello guys, how are you doing?

As the tittle suggests, its been quite a while last time I played WoW and even more so Warmane (im from Molten-WoW time lol). After quite some time away, i decided to play WoW again, but im rather new to the realms and conditions they have right now.

So, i would like to ask you all about the realms and the comunity as it is, like:

1 - What the diference between these 4 WotLK realms?
2 - Are any of them seasonal and will be destroyed, at some point?
3 - How toxic is the comunity (as i remember, quite so), specially faction wise?
4 - Is there any higher demand of classes and rolls?

I know this might seem a bit too much, but i would be really thankfull for any insight you guys give me. Ah, im PVE oriented, BTW.

Thank you all!

1. Onyxia is "Classic" realm (Max lvl 60 and so on). Loordaeron is WoTLK realm with x1 xp rate, Icecrown is WoTLK realm with x7 xp rate, Blackrock is instant 80 PVP WoTLK realm, Frostwolf runs Cataclysm expansion (no idea about the rates).
2. Dont think any of the realms currently opened can be called seasonal. Onyxia is about to progress at some point to TBC and further, no idea when and how.
3. Pugs seem quite toxic (at least horde side).
4. Usual Tank/Healer stuff. You will have instant RDF's as a tank, easier to get into raids as a healer tho.

Only "seasonal" is Onyxia. It's Vanilla-TBC-WotLK progression realm. After it ends characters can be moved to Icecrown, or retire them in Onyxia for eternal rest. It uses the same unmodified 3.3.5 client you use to play in Icecrown/Blackrock/Lordaeron.

Community can be toxic, it's pretty much the same on both sides.

Highest to lowest demand: Tanks > Healers > RDPS > MDPS.

If you're not new to WoW and are trying to 'catch up' then Icecrown is the way to go. Keep in mind, it is a pvp server so you need to have some tolerance and/or strategy (go to less populr zones) as you level. However, the main advantage is that its pretty fast to just hop on and play (high pop).

Lordaeron is a more authentic experience but much slower both in levelling and in getting into content (lower pop). Also, it is unfavorable for pvp players.

Blackrock is if you only want to play WoW for arena and battlegrounds.

Onyxia is a new realm, temporarily vanilla capped -- read Onyxia forums for more info.