Does the idea of "pistol start" from doom 1/2 work here? In other words, are the levels designed to be beatable in well done and under using a minimum amount of weapons and powerups? If so, what command can let me spawn into a level, "pistol start"?

That would be "pitchfork" start I suppose.
You would just hit T and type "mario E M" (for episode number map number) "mario 3 5", would start Episode 3 map 5, Spare Parts

Note, you will have to start an episode on Extra Cripsy first and then mario to the map you want.

There are a few of them here:
https://www.youtube.com/user/PostmortemThe