I made the mistake of leveling my new alt in Cataclysm: choosing this timeline thru Chromie, believing it would send me directly to Deepholm, but it didn’t!
Now I´m stuck in what is basically “updated Classic quests areas” such as Wetlands and Arathi Highlands… a complete and utter snooze fest and a a waste of time. 
Help! What do I need to do and what level do I need to be to get to Deepholm, please?
The big five Cata zones don’t open until level 30. Until then it’s vanilla zones.
You couldn’t do anything in Deepholm at low levels anyways. That zone requires flying for all of it which you can’t train until 30.
Ty Asana, will I get a quest to go there?
Or do you know who I need to talk to upon reaching level 30 and flying?
You can check the Hero’s Call Board, it’ll probably be there. Or you can just go the Earth Shrine in SW and talk to the guy who always starts it. 
What Asana said.
The only ways I am aware of to get into Deepholm without the quest chain are Warlock summons, and the Potion of Deepholm (which now requires level 31 to even use).
There are actually ramps to everything, but I wouldn’t wish that travel route on my worst enemies.
Agree, however, I have been very happy using a two seater flying mount to help a quester get around faster in Deepholm. It just doesn’t work if they can’t get into the zone to begin with, sadly.
There’s actually paths? I never knew! But I don’t think there’s a ramp to the flying airship. 