The first is a question directed at folks who've been doing the capitol city fires on both Alliance and Horde characters: Do you find that the Alliance fires are any more difficult to steal than the Horde fires?
For me, this is pretty much a realm based problem rather than anything else. My realm, at the moment, is very alliance heavy and while most of my characters are on alliance side, my horde shammy has constant trouble with things such as these. Killing the King of Stormwind is next to impossible on my realm and he remains the only leader that I need for the mount achievement on my shammy. We had a 50 people raid trying to down Varian (basically all 85 horde players on at the time) and yet the server is so full to brim of alliance that they can simply swarm us to death with ease as soon as we land our flying mounts.
The same goes for trying to complete objectives anywhere near Stormwind and sometimes Ironforge. There's always loads of alliance players outside SW. This has somewhat caused "alliance easymode" attitude for horde players on my server.
I've never had any trouble completing achievement objectives on my alliance characters because usually there's little to none horde players around and even if there are I can usually sneak my way around the few. If I have to fight guards I usually don't get disturbed by players either. (Not to mention that once I started actively playing my shammy I befriended most of the few active PVP hordies anyway, so they can see on Real ID that it's me on an alt messing around their doorstep.
So yeah, I have noticed some differences in difficulty but I blame them on imbalance of faction player amounts on my realm.