Some people like to flatten the tyre befor inserting the string.
I prefer to get the string in there as quick as possible - less pumping up afterwards. So I generally have everything ready to use before removing the offending nail/screw/bit of wood/metal. Oh and I think the string acts as a filler, not just to carry the glue.
Interbnal patches = dissmounting the tyre and putin it back on. Not something i can do beside the road easily.
I too usually run the tyre to its rubber end. It is my life and I take reasonable precautions.