yamatitan

Thats not how it works. You can add as many sub panels as you would like your service size is not getting bigger. Your limited to the size wire feeding your main panel and wire from the power company.

You can probably add a piggyback breaker to free up and extra space in the panel.

Make that 1" hole for the vanity light a 3 and 5/8" hole and put in a pop in light box and bring it up to code. Just a suggestion from a electrician. Also fish a new wire if possible instead of having a splice in your wall.

Bought mine from acme tools as well, cut in some receptacle boxes today and a island and it works great. The only issue is mine came with two wood blades instead of a wood with nails blade. Not a bid deal the other issue is the thing vibrates pretty noticebly I have had a lot of corded oscillating tools and none vibrate as bad as this one. I can live with it though dropping the cord and using batteries I already have a bunch of.