For future reference...Weldon has finally answered my questions:
Q1. Is there any preferred orientation of the pump and its motor?
A1. No. The pump can be mounted in the direction you require. It is recommended but not required that the pump be installed with the motor at least slightly higher than the pump head.
Q2. What - if any - filtration is needed? (Precision likes to have the filter between the boost pump and the mechanical pump when installing the RSA system.)
A2. An upstream Filter is recommended.
Q3. There are four plug holes around the perimeter of the pump. Is one left open for any fuel overflow?
A3. These are overboard drain ports. Upon installation, only one of the holes will be equipped with an overboard drain while the other three remain plugged. The pump does not leak normally. It is in case of a seal leak.
Tobi