I've played in only a PvP realm (Neptulon-EU), but I was always reading and learning the lore of WoW. I once went to Argent Dawn to RP, I joined a guild (a RP one obviously) and the leader couldn't really believe that I was RPing for the 1st time. This happened 1 or even 2 years ago, can't remember, but I saviour that moment like treasure, still. For years now I want to transfer to an RP realm, but I can't simply because I want all of my characters in one realm. I have suggested to blizzard many times to allow for a mass transfer of characters from one realm to onother since neptulon never got a free character transfer. I have 7 85s (Mage, Warlock, Hunter, Shaman, Druid, Paladin & Priest) and a 90monk. The majority are Night Elves with only the warlock being a blood one and the shammy plus the paladin being dwarves. I am saying all these because I have never really RPed seriously and thus this weakness of mine may lead me to commit serious mistakes in the story or setup or make my char much of a Mary Sue, so I would ask not to be rude in general.
Now, about what I've thought:
My Night Elf mage (which is my main in general) is (has to be, lorewise) a Highborne, effectively making him to be over ten thousand years in age. A good-standing member in the yard of Azshara. I do recognise how dangerous this is in terms of RPing it. I am really reluctant to do it, but I understood that in the end, how you use the ancient wisdom trait comes down to what you want to go for with your RP, meaning that you may emphasise in the character's shortcomings and such, since I also don't want to play some "being always right" char, but instead a member of the Sin'dorei or Eldre'Thalas, from where he left after spending most of his life conflicting with his compatriots, disgusted by what was going on there.
I do have many ideas and such which I won't list here because it will become too long, but... I would instantly realm transfer if I had a guild waiting for me, since most if not all of my friends have stopped playing on Neptulon and instead transferred etc, and I don't really see any reason to keep playing here, since I won't enjoy it. With that being said I also do PvE and PvP and I also really like them, but it's like... I really get kinda angry when someone passes by and his/her name is "loldpsbb".
What should I do in general? I've sucked the thought of transferring a lot, partially because I don't own a credit card or the means to transfer without asking some relative (I am 22-23 years old).
Well first of all, I did only ocasionally RP in the game itself, I usually keep to this Forum for doing so. So I can't really comment on the acceptance on the realms. But ties to Major Lore character are usually interpreted as Mary Sue characters, or at least are in danger of being recepted as such. This Forum explicitly forbids it for exactly that reason.
Aditionally, in this case, it isn't even really probable Lorewise. The Highborne following Azshara mostly, if not all, became Naga and Satyr. And even if you stayed an elf, leaving Azshara's Service (joinging the alliance) is nearly impossible. In the War of the Ancients she was described as astonishingly beautyful and awe inspiring and Illidan suspected magic in the workings of her beauty. So I would assume that she permanently has her court charmed.
From a quick read, since I'm not really firm in nightelf lore, most player Highborne (nightelf-mages) seem to be part of the Shen'dralar. I would personally recommend reading http://www.wowpedia.org/High-borne and rethinking the background.
Edit: This remarks however, are my personal opinion and a "lore check" I can't really tell if it bothers people on the realms that much.
Well, I've researched enough to know that there is a good chunk of highbornes who remained in their night elven form and did not become naga or satyrs and escaped to Eldre'Thalas. Lore-wise, it's ok. And no, I do not have even the slightest of intentions in suggesting some relationship with a major-role character. The kind of relationship a queen has with her hundrends of minions, yes, but nothing more.
Ah, that'S completely okay then. The "yard of Azshara" wording, for me, sounded closer to her than your intention. So the issue you were referring is the old age? That's rather neglectable, since there are enough rather old races, with the Draenei and the elves. It just boils down to your execution then.
Concerning addons, I only used My RolePlay, which lets you add appearance descriptions and background information for your character, for other users of the addon to see.
IIRC there's an addon called Gryphonheart Items that lets you create and exchange items in a separate inventory from the "real" one. Might be interesting to look into.