The advice I have for recent models is for ceiling mounting. If you do mount on the wall there is an option in the maps to set the orientation. Also in the maps you can turn on location readiness coverage, so if you upload the map, place the APs and draw in the walls you should be able to get an idea of the location quality.
The search field hover text says "Search by MAC address, IP Address, host name, user name or AP serial number. Partial and case insensitive searching is supports, but only the first matching value is located. The search checks clients, APs, and devices, in that order, for possible matches." I've just done a user name search and it worked, although I generally see rings for location as my AP coverage isn't sufficient for triangulation.