Hello, I have a 100 amp electrical panel and I am wondering if it is maxed out an if I wished to add anything it would need an upgrade? I have attached two pictures of the panel. The main reason I ask is that I have a 30A breaker right in the middle that seems to have nothing attached to it. I am guessing there is probably a valid reason for that, but thought it didn't hurt to ask before I call a local electrician over to my house.

I wanted to freshen up a painted room with new switches. Everything appear to be working correctly however, I hesitate to open all the wiring in the box because the wiring is very old (60 years). There are soldered and friction tape connections and the switches are vintage 50's. I am finding similar connections elsewhere in the house and I am leary to touch them too much in fear of breaking a wire or loosening one of the old connections. Should I be opening everything up and remaking these old connections? Or would you just replace the switches and call it good? Or don't disturb them at all... if it aint broke don't fix it?