The necrobump is okay in the sense that you're needing help with something. That's fine.
The thing you're trying to do is going to require some DIY. The Master Levels were intended to be played individually; even with this menu interface, all it does is remove the need to quit and restart Doom every time you want to load a new map (it's essentially a recreation of the original DOS menu, just in-engine). As far as I can tell, even WadSmoosh enforces a pistol start per map, which is true to the spirit of the original files.
The problem I'm seeing here, though, is that while, again, it's fine if you don't understand the instructions because they're not exactly the kind of thing a regular, ordinary Doom player will be doing every day; I don't understand getting bent out of shape about it. Especially things like this:
(that means I want to keep my inventory dammit, don't tell me to spawn weapons)
I have all it takes to run a mod goddammit, why do I have to be bothered with taking even more steps like downloading an extra program to edit something that I don't even care to learn about?
can't anyone just help me out here and send me, like a readily available .wad or something?
I'm the one who needed help here, not anyone else, you seem to be slow to get that notion.
This doesn't really strike me as the kind of respect I'd like to be seeing around here. Asking for help is fine, you're not breaking rules just for that. But I would really prefer if, in the future, you tried your best not to take your frustrations out on a userbase that ultimately has little-to-nothing to do with why you're upset.
I would help you myself, but I don't actually own the Master Levels (I'd need to buy the Doom Complete pack on Steam to get them nowadays, if I recall, and that's not cheap when I own the rest of the series already several times over).