Two c's in Succubus
I cannot resist this kind of project so Maexyn ran around for about three hours and got herself a Succubus. She picked up flight points for Menethil Harbour, Auberdine, Astranaar and Ratchet. Running through Darkshore and Ashenvale reminded me how vast and annoying these areas are, it was slow enough rep grinding with Maevyn on a normal mount, there is no way Maexyn is levelling there, I'd rather do Wetlands and Darkshire for the fourth time. The killing involved in the Succubus quest was quite straight forward, it is easily soloed. She did most of it except for the final Succubus taming at level 20, the quest before last in the chain dinged her to 21. Warlocks were virtually queueing for their Succubii at the end, two other's left the Slaughtered Lamb at the same time she did.
I haven't had time to try out the Succubus yet. I'd put up a screenshot of her but it's far too naughty and, being a warlock pet, it looks like every other Warlock Succubus. It's hard to warm to a warlock pet in the same way you do a hunter pet, even one that wears a thong.
Must work on Maexyn's 'armour'. I haven't done much in the line of upgrading it since level 14.
Fighting Style
I'm putting points in the talent that stops drain life being interrupted as I'm aiming at drain tanking and I'm not sure if it is viable yet with only rank two out of five. Soloing with the Voidwalker is still perfectly ok. I still haven't used the Sacrifice Voidwalker spell.
I've been mixing up my attack a bit. I have been opening with Curse of Agony and then sending the Voidwalker in. The enemy runs to Maexyn but as curse of Agony is low threat the voidwalker easily pulls agro, leaving Maexyn free to cast Corruption and Immolation. The difference this makes is that the enemy runs to Maexyn instead of the pet running to the enemy, Hunter Style. I don't feel that at the current levels keeping range is as important for the warlock as it is for the hunter (there is no minimum range) and having the enemy close means a shorter run to loot it's corpse. Maexyn does not seem to draw agro very often, even fighting close quarters. As I say, I'll probably have to review strategy at higher levels but I also have to remember that Maexyn is not a hunter.
Group Invites: Mystery Solved
I installed the AutoDecline mod because of all the annoying group invites Maexyn was getting. It works nicely, I just get an entry in the chat log to say that so-and-so's group invite was declined. I did some /who's on the names and they were level 1's in Elwyn Forest so it looks like a gold selling thing. Maexyn's warlock skills aren't in as much demand as I thought 
At least she won't get a group invite in the middle of a big fight that has gone tits up.
Plan
I'm going to try and be less fixated on running one character at a time and instead alternate between Maezyn and Maexyn and exploit rest bonus more. I am lucky, I have two viable characters that I enjoy playing and being 20 levels apart it means that there is a few week gap between doing an area on one character and repeating it with another.
Peter's Moblog
Good to see AutoDecline working well. As for the level 1 invites, as you suspect, they are gold sellers. If you accept the invite you get two or three lines of party chat about some gold site then they disappear. The lengths the gold sellers go to are amazing, they must spend hours thinking of new and innovative ways of selling their enormous stash of gold. Another addon you might like is SpamSentry; it blocks all gold spam and builds a list for you to report to Blizz. I think the theory is that the more Blizzard gets spammed instead of the players the better, as they might take notice and do something.
Also, as you hit around 35 with Maexyn, don't forget to start the chain quest for the big purple sea monster (Tethyr) in Theramore - it's a fairly easy fight but good fun to see everyone getting blasted off the piers with jets of water from the monster :)