I use Openelec as well v3.95.1 and Gotham test, I didn't noticed the latency but I have software bugs.
Look at MrNice posts in Raspberry Pi support.
To record the other keys, you could use the full keyboard in the GUI and choose in this page the control you want:
http://wiki.xbmc.org/index.php?title=Keyboard_controls
I is working fine for me.