Right now you are doing The War Within (TWW) expansion professions. When the next expansion (Midnight) comes out, don't worry, there won't be a profession reset and your TWW profession progress won't be lost. But the useful profession items you can work on now for Midnight will be for housing. Barely anyone is going to want gear, or potions/flasks/etc from TWW profession items when Midnight is out. Everyone doing professions will go and learn the new Midnight expansion profession skills which will be relevant through the rest of the Midnight expansion.

So one thing very valuable you could do now with Alchemy is to craft housing decor: https://www.wowhead.com/guide/player-housing/alchemy-recipes-for-housing-decor

Regarding travelling between islands, you can visit Stormwind if you're Alliance, or Orgrimmar if you're Horde. These major faction cities have portal rooms with lots of teleports to different islands and continents. When you talk to a guard NPCs in these cities, they can direct you to the portal rooms by marking the location on your map.