Most discussion of the RT3200 / E8450 has been in this thread: Belkin RT3200/Linksys E8450 WiFi AX discussion Every owner of one of those routers should read at least part of it.
Just to be clear, as far as software goes, the E8450 and RT3200 are exactly the same. The only difference is the E8450 has a black plastic case and additional status LEDs on the front. The RT3200 board even has places for those LEDs, but they are not installed.
Yes once OpenWrt is installed you would ssh in via a LAN port. Since you'll be flashing a snapshot build, the web interface is not present at first, it needs to be installed separately via SSH.