Replacing Fuel Sending Unit

Issue #1 - I am replacing the fuel sending unit in my 1965 Valiant Base, Slant/6. I was given a GT-FG69A O'Riely part for the job. Do I need the special wrench to get the metal/gasket retainer off? Can I assume that I just pull out the old and push in the new, without dropping the tank? Any special tricks along the way? The tank is less than ½ full.

Issue #2 - I need to mig weld in some floor pans, so I want to remove the fuel line from the tank to the fuel pump and cap off each end. Any suggestions on what type of fittings to use? I assume this practice is safe, even with a 1/2 tanks of gas.

Staying Safe In Kansas City, Mo.
Thanks