In my experience, the bit should not be fully seated in the collet but should be about 1/4" from the bottom. The taper of the collet and the collet seat work together to grip the shank of the bit. Personally, I consider half the length of the shaft to be the safe zone.
Bushings are an excellent way to expand the versatility of a router. Using templates, you can really make the tool rock. By design, the bushing will limit the depth of cut slightly but if you need a deeper cut there are methods to fix that.
Certainly not a stupid question. Routers are one of the most under-utilized tools in the shop.
Artisan Woodworks of Texas- www.awwtx.com