The advantage of a WLC is that you get centralised management, better security and more features since all the APs act as basic radios and tunnel everything back to the WLC. Make sure to configure/upgrade the APs before you mount them! You powering them using a PSU or POE?

Not sure how viable this would be for you but if you can then you should get all the hardware together before its mounted so you can work out how to configure it. Mistakes at this point would be easy to correct and wouldn't mean you trekking around the building trying to access a AP or switch thats embedded in the wall or ceiling.

I would have put a EtherSwitch module into the 2921 and skipped the extra switch in the wiring closet that the router is in. This would mainly be for space saving reasons rather than management as the ESW is managed separately even though its inserted into a router.

It'll be a good learning experience for you. Always good to have Cisco experience on the resume/CV