Hi Bill,
here are my answers

Questions:
1) What are the differences between the two machines besides, rod/rail, software: V2/V3 compatible, and work size?

V2 Software is included for all machines and V3 compatibilty is given for all V2 machines.

The precision increases form rod (belt) >> rail (belt) >> rail (spindle)
Pin pitch >= 0,65mm >= 0,5mm >= 0,45mm
Motor Stepper closed loop stepper closed loop AC servo

2) It looks like the used component tape on the 2500DP flows through slots in the bed and out the bottom of the machine. Where does the used tape go on the 2500D?

The 2500D moves tape over the working table to East and South side and have sheet metal separator between them.

3) Does the 2500DP have larger stepper motors? What is the advantages of that...faster head movement?

We use closed loop stepping servos for faster acceleration and speed.
The machines are bigger and more mass need to get accelerated!

4) What reasons would I pick the 2500DP over the 2500D?
Mostly because of better precision and bigger working areas.