TOPIC: Tempo long 18 gal fuel tank line

I have an older metal fuel tank in my boat. It is a tempo L-O-N-G cruise 18 gallon tank and have a few question.. It looks like the fuel fill line up to the fill cap is cracking. It looks like it is rubber but possibly metal lined? What do I need to get to replace this line, is it a special make custom ordered? Inside the tank for the outgoing line, is there a rubber line inside the tank and possibly a filter? I have never opened the tank up as I never had a problem with it and sending unit works fine. Found you usually create problems by trying to do preventative maintenance. If I do open it up, I assume there is a gasket that will need replaced? Lastly, I believe my fuel line is 5/16 but I was thinking of upgrading to 3/8. Can the outgoing line fuel fitting be changed? Thanks.