My friends IRL started together with me on WoW. They all more or less did pick a character that is on the eastern continent.
One of my friends walked for an hour orso yesterday to get from tendrassil to dun morogh.
Im thinking of doing it as well and teaming up with them.
But I am not finished with my quests on the dark shore (need one more in tendrassil) and still enjoying it.
What is a good way of doing it?
walking there for this once and leave the heartstone in auberdine to get back whenever I want to (and fly there and back again) or walk that way, leave my heartstone in for say ironforge and use the teleport moonglade to get back and forth? (typing this now seems to be the best option.. the teleport doesn't have a downtime).

well oke.. are there any good quests in and around ironforge for a night elf druid lvl 12??

That's pretty much what I did... around level 12 I packed up and relocated to Ironforge. You can pick up the quests in Loch Modan and then later the Wetlands.

so it is worthwile to travel that way..

And also, since your a Druid, you should have the teleport spell to Moonglade by now. So you don't even need to leave your HS for Auberdine. Make the trek to Ironforge, set your HS there, and life will be much easier. Also incase you didn't know, there are 2 Flight Paths in Moonglade, the Druid only one, which will take you Darnassuss if you are Night Elf, and Thunder Bluff if you are Tauren. And then if you go NW I believe of the Druid FP, there is a General Alliance Flight Path that actually flies to Auberdine, and later on in the higher levels, goes to Winterspring.

At like level 12 I banked my gear and ran naked through the swamps. (Hit the flight masters in Menethil and Loch Modan) Bound in Ironforge once I got there and never really looked back. Had easy access to both Kalimdor and Eastern via teleport and stone respectively. Finished up my Darkshore stuff then was completely floored by both the aesthetics and depth of scripting in Dead Mines. Ah, the good 'ol days.

You are better off binding around DM. The dorf and human lands have enough quests to take you through the levels until auberdine is greyed out for the most part. I've always felt the NE lands sucked for levelling up early on, because Kalimdor zones are just too big. You spend way too much time just running around w/o a horse.

Yah, but don't forget to do enough NE quests to get your honored status, so you get your riding kitty 10% cheaper. I like the look of the Dorfie and Human lands better, really dislike all that dimness in the NE areas.