Hi
Those links contain datasheets: (each datasheet contain the info u asked in the last pages)
they will give u the antenna pattern plots.The distance is in Wifi is an issue based on a lot ot variables (Radio / building/floor topology/ energy saving mode,client antenna,driver,software,band and much much more)
U may use VisualRF with cad files (and good dimensions) to get a good idea.
http://www.arubanetworks.com/pdf/products/DS_AP90Series.pdf
http://www.arubanetworks.com/pdf/products/DS_AP100Series.pdf
http://www.arubanetworks.com/pdf/products/DS_AP124-125.pdf
regarding maximum clients - it's depends a lot of things (spectrum usage,client user type,services,location,signal level and much much more) - I personally don't like to connect more than 25 users on 1 radio module
please read the following thread:
http://community.arubanetworks.com/t5/Access-Points-and-Mesh-Routers/Max-number-of-conccurent-users-AP/td-p/12567
http://community.arubanetworks.com/t5/Access-Points-and-Mesh-Routers/AP-93-maximum-concurrent-users/td-p/15051
More benchmark info (for other AP module)
http://www.arubanetworks.com/pdf/technology/TB_Wi-Fi_Benchmark.pdf
regards.
Me