I'd recommend against fermenting in the bottling bucket because the trub will foul your spigot. Sure it can (must be) cleaned, but why deliberately gunk it up? For your first couple of kits, just follow the instructions. Yeah sure, you could leave the beer in primary for an extra week or two if you want. The important thing when you're starting out is to develop solid sanitation habits, getting used to working with the ingredients and settling into a good workflow.