Gas Tank Replacement - ID Help

I want to install a new tank on my Duster.............atleast I think I want to

Its the factory tank and I have no idea whats inside the tank (nor the condition of it)

Should I remove it and have it cleaned or just remove it and buy a new tank?

I see they sell tanks with 4 vents and tank with no vents, etc.........stupid question, but how can I tell what I need?