If you are going to tile the shower pan, I suggest you go over to www.johnbridge.com lots of good tiling info there.
Ideally, the drain is in the middle of your shower floor. Once the drain runs horizontal, it should have a slope of 1/4" per foot. Also note that a shower drain should be 2". You also should have a vent line running off of the drain. It depends on the type of shower pan you use how high the drain needs to be. My unprofessional experience.