Fuel cell

I have to ditch the gas tank in my Astro when I bodydrop it and I'm going to go with a fuel cell. I've been looking through Summit racing catalogs and others, and I see some of the tanks with built in GM 0-90 ohm sender. What's that mean? Is that with the fuel pump or just a sender for the gas gauge, and if it's for the gauge is that the type of sender I need? If fuel cells dont come with the fuel pumps in them, what type of inline pump should I go with? I need some help here....