What do you make of this color? Is this just the gasoline or the inside of the tank? There are two different shades of the interior of the tank. A silver color and a rust color.

 

Kind of hard to tell. Tank pictures are tough.
The silver part looks normal. I would drain the fuel and check out the rust looking part.

 

Looks decent enough, but if you're really worried, you can drain it and clean it. Best way to do that is to get a bunch of white vinegar (you can also put baking soda in with it, or some BB's), and fill your tank as high as possible. let it sit for a day or two and keep checking back. you can keep it in there for about a week at most before I would clean it out. once it's clean enough to your liking, drain it out, and use a high-pressure water source to clean the tank as much as possible, spraying from the lid and the petcock hole to get everything out. Let it air dry, and you should be good to go.

 

Vinegar is an acid, baking soda is an alkali - they will neutralize each other. The only reason to add them together is if you're trying to create a weaker acid, or a weaker alkali. The correct combination will create a neutral solution which won't do anything useful.