Wookie,
Empty or full, either would be a great help. And due to the location (roof of work) pr0n or anything to do with hacking would be a big no-no.

I have a 2.4Ghz box which I plan to put onto the AP.

I can't get it from my house however it is a fairly trivial process for me to connect to it from work
If it needs to be moved to the north a little, so be it

On that note... is there an adjustable downtilt device, maybe adjusted using a thread or something for fine adjustment?

Cheers
John