What should the pressure be on my gas boiler?

I have an old gas boiler from the 50's or maybe the 60's. I'm trying to find out what the pressure and temp should be at 65 degrees. It is typically around 110-120 degrees and pressure is around 14psi when the boiler is not running. It goes up to 17 or 18 psi and around 140-150 degrees after running. Does this sound right? Also, would the pressure/temperature increase if I turned up the heat in the house and would it go down if I turned the temperature down? Finally, the heat has not been on for a week because it's been warm but it will be cold tonight. There is a metal expansion tank attached to the boiler and hung from the ceiling. When I knocked on the bottom of it, it sounded hollow or empty. Is this good or bad? Sorry if these questions sound stupid but this is the first house I've had with a gas boiler, the other house had a furnace. Thank you.