Is it a Sharp one? Sounds like it from the model number. I've found a manual for a different model at www.minidics.org/manuals/sharp_mdmt831.pdf
It lookds pretty similar to the manual for mine, so I expect it should answer some of your questions.
The TOC edit thing appears when the minidisc is altering the table of contents on the disc - ie its making permanent the changes that its been working on. Its important not to remove the power source when its doing this, as the disc could then be corrupt & unreadable.

Mine also has a 'hold' function which you can turn on & which then makes all other button-presses inactive until you turn it off again (to prevent accidental button-presses from knackering whatever it is you are trying to do). Unfortunately I accidentally put hold on the other day & then I couldn't remember how to turn it off again - and hence couldn't do ANYTHING including turn the damned thing off!!! its worth looking that one up in the manual..... (eventually I turned it off by frantically pressing everything I could in all sorts of combinations).

Kris