Some info re. accommodation . . .
Obviously, you are likely to get cheaper room rates the further in advance you can book, so there is a bit of an incentive to get the date finalised early. I suppose it's a trade off between getting the best rates and being certain of the date.
The location would be AB15 and there are two hotels within walking distance of my house (which is about 14km from the airport and 6km from the train station). Depending on your budget, you have
The 3* Cults Hotel, ~750m
http://www.thecultshotel.co.uk/
Room Rates, Double Room, £75 with breakfast, £60 without per night
I have never stayed there, but the restaurant is nice and the rooms look good on the web
It is pretty small though, so early booking would be advisable, this is probably the preferred choice
The 4* Norwood Hall Hotel, ~1km
Room rates, about £80 per night booked direct, you may get cheaper on the web
http://www.macdonaldhotels.co.uk/our-ho ... all-hotel/
or Booking.com
Again, I have not stayed there, but it is bigger than the Cults hotel, so you probably have more scope to book a bit later
The 5* Marcliffe at Pitfodels, 1.4km
http://www.marcliffe.com/accommodation.htm
Say £300 per night, pretty popular for weekend breaks so you're not likely to get in anyway

I have stayed there, but I can't imagine the rate being popular for Memofest
Aberdeen City Centre has the usual range of budget hotels
Including Travelodge City Centre, about 6km from me
Rate depends on when you book, far enough in advance and it would be £65
It's a Travelodge - you know what you're getting
any questions or requests for more info, just ask
regards
Dave