I can tell you from those photos that it's rusted through in spots. I bought a second body shell for my build that had that same bubbling paint. I thought it was surface rust as well, until I started poking around on it with a flat screwdriver. There were holes everywhere. Paint will hide a lot. That said, I was about as green as they come as far as auto body work goes. Don't let the rust scare you. These are great vehicles to learn new things. Take scrapdaddy's advice. You are way ahead for posting your thread and asking questions. I wish I had done that before I bought my first one. Let's just say it was an expensive lesson learned.
Good luck.
Good luck.