A bit of progress on #2
As per the manual,
RN_SETRANGE STARTTRACK/N,STARTLINE/N,ENDTRACK/N,ENDLINE/N,TRACK/K/N,
LINE/K/N,CURRBLOCK/S,CURRTRACK/S: Sets range. Can specify
absolute values, or range a given line/track, or range current trk/blk.
Commands like "Ctrl-B" selects the current track as the range. The octamed command is "rn_setrange currtrack"
A custom command with "rn_setrange line 1" will select line 1 as the range.
I just need the command that sets a range in relation to the current cursor position on the track editor, like holding down LMB accomplishes. But I want to hold down a key, and move the cursor keys, selecting a range as I move around the cursor.