The 8' is typically very conservative. You could do a fairly easy test to determine if the higher drain height is ok. Simply put the system as it currently is into regeneration, time how long it takes to remove the water from the brine tank. Relocate the drain temporaily to the new height and repeat. if it is nearly identical (the time to remove the brine water brom the brine tank) then you should be just fine. The drian height limit is based on the ability of the venturi injection system to overcome the backpressure of the drain. In general, higher incoming water pressure allow for higher drain lines. A larger drain line is unlikely to help, nor will it hurt. Larger drian lines are recommended for longer runs to reduce the frictional pressure issues, and excessive noise due to velocities rather than accomodate for height.
Condensate pumps are great, but check their capacity. Some will not flow at the rate you may need. Condensate from AC units etc. tends to be very low. Also, when one fails to work, where will the water go?
Hope this helps.