Spawning and removing props on startup

How would i go about doing this?

And if i was to do this, how would i go about finding a vector? (i know spawning them requires a vector, i think.)

Hook into InitPostEntity and use ents.Create() and go from there.
If you want an arbitrary position, you can use the getpos command in console to find the position where you are standing and check what map it is (game.GetMap) to verify before spawning.

To make an arbitrary vector, use Vector(x,y,z).
Ex:
Vector(100,100,128)

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