Psilous brings up a good point: it appears your command parameters are possibly incorrect, at least, mine are different and they work fine:
+sv_cheats 1, developer 1
Even then, i don't think entering those commands wrongly would give you that "missing dll" error... Post your Game Configurations and Build Programs if you want, as i think the problem is more likely to be in there. I would also recommend using
SUBST command to shorten you steam paths, making your filenames more manageable to troubleshoot. (if you haven't already)
Also too, as i think you already know, having hammer launch the game for you is generally not a good idea, as hammer 3.x is buggy and unreliable at as it is, and the less you let it do the better.. =)
Potato: sorry i ninja'd your post! ='(