you can do both mesh and client access on 5Ghz. If the client load or bandwidth is low, you should be fine. If there is a need for high bandwidth or more than 10-12 clients, 5Ghz should be reserved for mesh only (on IAP you would just make the VAP 2.4Ghz only).
LoS is preferred, but if the distance is short you might be able to get away with no LoS, but it's not recommended and performance may be poor.