What are the legal issues about:
Using Q3 BSP File format( gains: except from our level files, all quake 3 mods can be played or at least easly convertable to our engine-game ),
Using Q3Radiant for making our game levels ( gains: no editor writing, no new editor learning for our artists and all the people who will make mods for our game)
Maybe we can also have an editor which takes level files as q3 bsp. In this editor, there would be no modeling, just additions for our game would be made. for example character descriptions etc.