Classic [Need Advice/Help] Returning player since Wrath needing a lot of catch-up.

So just to preface this post, let me provide a little bit of background.The last time I've played Retail WoW seriously was in WoTLK. I raided ICC a bunch, then took a long break until Mists of Pandaria. I played a Druid mainly and was sad to see they turned Tree of Life into a 30 second buff on a 3 minute CD and apparently removed Insect Swarm from Boomkins which totally blows my mind as Insect Swarm was one of their main DPS spells.I'm thinking of coming back to retail in Shadowlands, but I don't fully know of everything that has changed since MoP or even WoTLK. I'm used to the WoW where you'll see people dueling/pvping outside of orgrimmar..how common is that now?How abandoned/plentiful are the cities? If not, where is everybody? How hard is it to find a group to level with?I played on the PTR a little bit and apparently you're able to solo some old raids by yourself.. Is there any way to make them harder/not as "solo-able" for better gear/exp?I've also heard the classes have changed pretty dramatically, like there no longer being 75% of the abilities to even fill up a spell bar. Is this true?I know there's a lot of questions but I have NO idea about anything that's going on and am hoping someone can catch me up/fill me in on everything that's changed since I last played.Thank you. via /r/wow https://ift.tt/3sA34I8