Looks an very interesting level. Will be it an really hard map? One of these pictures haves 2 Superarmors and 3 Large Medkits. This WAD would be quite fun to play combined with the Simpsons WAD (such all others).
-------------------- Now I leave my IPS patches of my hacks for everyone play and edit as you want to.
Just for those wondering, zDoom is a port that allows you to play Doom games (.WAD files - i.e. "doom2.wad") there's tons of other ports (prBoom, GZDoom (like zDoom but runs in OpenGL or something), Boom, Doom Legacy, Doomsday Kickstart, Gdoom, jDoom, etc.
For sprite/music/GFX/SFX/Palette...(everything except level) editing, I recommend XWE (eXtendable Wad Editor). If you don't own Doom, and you don't want to pirate, download FreeDoom. It's a huge WAD that replaces everything in Doom with new things (and it's legal) - basically a game of it's own. Download FreeDoom here:
For LEVEL editing, I recommend what Sagittarius said - DoomBuilder. That's pretty much all I have to say.