i says use the tools @ disposal. missions i can make, textures i can obtain, hell even the ones in the game will be fine as well as FS textures, thats how i made some walls. then theres the models which can be made by anyone with modeling skills.
if ur a participant in the counter strike or half life forums and or games and comunities ask around. theres also tons of models made for half life. where r u having the website done @? if u got aol/aim: im me @: Deep Eyes NY if u wanna talk, ima be on for awhile.
BTW though, yes worldcraft is established etc, i think quake 3 arena would make a better engine. the mission editor has as many resources but nobody i know is familure with it, i sorta lol, took a class for worldcraft in a community center (federal dollars @ work for you!), and yes it is easier to use, i would prefer worldcraft for quake 3 but its a pain, then theres quake 1. which is hella easy to mod.