dev is right, the foam prevents sloshing, which if you've ever drove a tank vehicle you'll know why they put baffles in them, the foam in a fuel cell acts as a baffle.....and it will have to be replaced every 2 years or so... he also posted a good link to aeromotive, their site has a bunch of good plumbing diagrams n such on it....
you could use a small inline electric pump and the check valve to supplement the oem mechanical pump if you wanted, just don't get one that pushes much more than 5 psi....
here is a pic of my setup from the start, but it is still not finished, it will give ya an idea..