It looks like mc is just in extras-devel at the moment. There's a warning on the packages page saying that it's not been correctly assigned to one of the approved application sections, which is probably what is causing it to not be installable through the application manager.

If you want to install it through terminal, enable the extras-devel repository in application manager (warning, stuff from this repository is by no means guaranteed to work, and because of it's nature (development software) it can cause unexpected side-effects on your device) then you'll need to do the following:
Make sure you have rootsh installed.
Close application manager
Open terminal
Afterwards, remember to disable the extras-devel repository again.

If you install openssh you can do a few things:
ssh over to the device and type on your computer, and the commands will run on the device.
Copy (scp) the files from your device to your computer, edit and then copy them back.

Essential applications - I think there might be a few threads on this - have a quick search and see what you think.

P.S. I prefer geek, to boff