Returning Player – Is Low-Level Dungeon Content Still Active?

Hi everyone! I used to play on this server back when the level cap was 39, but had to take a break due to becoming a new dad. Now that things have settled a bit, I can dedicate 1–2 hours in the early mornings to play. I'm planning to level up a new character and would love to experience each dungeon through RDF at least once, complete all posible achivements posible like Loremaster and explorations, I know that is a long run but I have been playing on several servers since 2012, I dont want to jump to another server any time soon. I love completing the quest learning the Lore and exploring each zone.

1. Is low-level content still active and queueable these days?
2. Xp can be set x1?
3. Also what class/spec is the most required in end game dungeons? I dont think that im able to join Raids due I have a small time window to play

Thanks in advance!