I wasnt sure which forum to ask in so if there is a better one please let me know. I am running a new cable connection to my bedroom through the floor from the garage underneath. I have taken down a piece of drywall to gain access. I can only get a rough guess of where the wall is based on a floor vent on one side of the wall. I think the wall may be directly over a joist but I am not sure. I am trying to figure out if I should drill from underneath or try to cut out the whole in the wall for the cable outlet box and try to use some sort of extension and drill down. Any suggestions?

I read once that in some commercial applications it's common to have separate breakers for every outlet and light fixture. I assume the reasoning for this is that if one breaker pops open it won't interrupt power to anything else. Would there be any merit in wiring a house or shop / garage like this? It would seem cost prohibitive for a little more convenience, but can anyone think of a reason to do this?