“No HISTORY. You can repeat the last command by pressing the right-arrow“

IIRC, there’s some limited command line editing support using the function keys. You can also get command line history using https://en.wikipedia.org/wiki/DOSKEY (if your DOS has it)

“So figuring out the available commands is using a lot of DIR .EXE's and DIR .COM's.”

Try

  C:\> DIR | MORE

(Alternatively, redirect the output to a file and use an editor. I think your DOS has edit.exe, but EDLIN is the true way)