1. I guess you have to open dictionary first. Then it works like that. It is IMO fully satisfactory. And the firmware evolves so maybe there is even easier way, now. I do not have the latest firmware.
2. I do not know what NCX file is.
You have Next/Prev, TOC, GoTo #, page slider, crosslinks, Back to Previous Position, Go To Note #, Go To Mark #,
and possibly some more.