In a case like yours, I'd rename the autoexec.cfg to something else (like cheat.cfg) and bind it to a key through the console. I'd imagine that these commands don't work unless you're already in the game, by which point autoexec.cfg is worthless.
That sounds very well and good, however, my understanding was that autoexec.cfg is loaded automatically when zdoom or in this case, GZDoom, is started up. And it does not load automatically, at least not for me.
Certain commands need to be executed from within a game. I'm not surprised the first 3 are not working, the fourth one I would have expected to work and the final one certainly should.
As an aside, I've found it very frustrating that Zdoom stores the full path info for the autoexec in its ini. If you ever move/rename/copy your directory, you have to go in and edit that path entry. It works just as well if the line only reads autoexec.cfg without the path, provided that you have the autoexec file in the directory that you ran Zdoom from. Surely most people will be loading their autoexecs from the current directory, so there is no need for full path information in that case. If someone wants to load an autoexec from somewhere else, they'll have to edit the ini file anyway. IMO, Zdoom should just default to not putting in path information and allow Zdoom to still read/process path info should it be entered by a user. (At present, if you start Zdoom for the first time without an ini, it puts in the full path info for the current directory.) I know, wrong forum. I'll maybe post this as a feature request over at Zdoom.org
Oh, and whilst we're on about ini's, I think I'm right in saying that GZDoom still uses zdoom.ini, and adds OpenGL (etc) settings to it. Any chance it could use its own ini by default?