I have a basement where it looks like the shower drain in the floor is only about 6 inches from the cement wall. I am assuming that if I want to use it where it is and use a pre-formed shower base, that I would have to raise the shower floor to accommodate the 1/4" slope I need to drain the water from the pre-fabed shower over to where the drain actually is. Right? Otherwise I could install a custom shower and have the drain wherever I want it.

Yes, it appears that your basement drain is set up for tub installation. Kohler now makes shower base that can be placed in place of old tub therefore with drain 6" away from wall. I have seen it in Lowe's on display. This way , you don't have to build step or do anything else - just set the pan.

So your saying that the base pan has an offset drain to accommodate where the drain location is? But if I don't go this rout I would need to raise the shower base to I can run the pipe drain over to the drain in floor?

Yes, and Yes to both of your questions