Chad,
In building B do you need to provide ethernet clients access to network services from building A ????
If you do then you need to use bridges.
As to how many devices and their placement you will need to do a site survey but the optimum way to so this would be
Bld A BR350(or BR1400) ------radio link---- Bld B BR350(or BR1400)--- Router
Of a second ethernet port of the router have a AP1100 or AP 1200 to provide users inside building B coverage and a second AP to provide users at the pool access
The router is there to prevent broadcast from clients at the pool or building B from tying up reasources of the radio link to building A and to give a point where you can implement layer 3 QoS and security policies You can do this without the router but you have very little control over your traffic and will have a big brodcast doamin. This will depend on the number of users.
There is plenty of other options but this is one of the best although more expensive than others. I recommend you talk to a Cisco reseller or your account team as they will be able to get someone to look at your site and go through the different options with you.