Can I use DOOM editors in a DOS emulator? And do they have to have DOOM open at the same time?

Answer 1

I haven't yet successfully run any Doom editors in any way shape or form in windows xp. I've tried dos emulators, win 95 emulators, everything, and it's just not happening.

I bought a second computer so I could make doom levels again =)

No, doom doesn't run at the same time. But keep it handy as you'll have to test your mods as you make them.