Asus RT-N66U vs Asus RT-AC66U Router



I'm looking at buying either the Asus RT-N66U or RT-AC66U router for my home network this next week. Both routers seems to have similar specs, settings, and wireless modes (except the AC66U is capable of 802.11ac).

Can either router be set as a media bridge?

Is it possible to activate only one of the wifi modes? For example, if I only want my network to operate on 802.11g, can I lock that in?