A few questions about my new gas tank

I used my old straps with no problem. As you described yours I think they would be fine. The only problem I see with the film on the tank is that it might collect dirt, don't believe I would be concerned with the inside. Wish I had taken pics of my old pad and new installation but it was pretty straight forward. Lay the pad on the tank as it looks like it should go and adjust for best fit. Sorry I am of no help on the tube as mine did not have that.