In case you dont want to have a visible beard i really recommend you wax your face, or at least shave before heading out to con and put some powder on to mask the beard a bit (but since you're getting makeup anyway, thats covered). Just dont underestimate how quickly a beard regrows, mine went from smooth and barely visible (i have dark hair so even if i freshly shaved its still visible a bit) to scratchy and well visible to the naked eye within half a day. Waxing simply keeps your face clean for weeks, although i havent done it yet (but next time, i swear to go, I WILL).
Shaving legs is actually rather easy if you want to do it, i would at least recommend it if you have to show skin around there, though its not 100% neccesary (and I found that thighhighs slip down more easily on shaved legs), you can essentially use a face razor for it, though there are also specialized ones. Just remember to be very gentle, otherwise you will scalp yourself instead. I recommend you do it a couple of times several months in advance to get the right feel for it so you dont have to go to the con with half your skin missing.
What you probably wanna look up a bit too, is kind of the behaviour and phrases that are associated with maids. It will definitely amaze people if you act authentically.
Female Natsuru Senou (Kämpfer) at Gamescom 2014
Char B1 (Its a TANK, its not from an anime, unless you mean Girls und Panzer)
Kaito Kid (Detective Conan/Case Closed and Magic Kaito)