As to your question about the the fuel flow, or lack of it. You have two tubes going up into the tank. One is shorter than the other one and both have wire tube type filters on them. Really old gas can congeal on these filters and stop or slow the fuel flow out of the petcock. Also the petcock is made of aluminum and over time can oxidize and get completely stopped up. Remove the two screws holding the petcock and very gently rock it back and forth and then pull it out. The rubber seal under the petcock can possibly be cleaned up and reused. NEVER put carburetor cleaner on rubber or other gaskets. If it has been sitting several years, the tank is probably full of rust and will need to be cleaned and resealed. If it's long lay up is all that is wrong with the bike, it can be gone thru and cleaned out and made to run again. Might want to try and turn the motor, by hand to make sure that it isn't stuck. If it turns then take out the spark plug and put some light oil into the cylinder and then turn it some more to coat the cylinder walls and rings.
Cleaning the carburetor isn't always a DIY project. Might want to get someone to help you with that. It's not a hard job unless you've never done before.
Hope this info will be helpful to you. Good luck.
Mac, aka "ole two wheels"