PRC controller described a minimal separation event caused by questions raised by an IFR departure; the reporter claiming new questioning procedures regarding departure climb outs are confusing; adding that SIDS should be developed.

Narrative

New procedure requires Ground Control to ask IFR departures if they are not on the ODP (obstacle departure procedure); will flying runway heading until 7500 allow the pilot to maintain their own terrain separation. Most pilots either mistake the question as a restriction or do not understand at all. Ground got an affirmative on the question from Air Carrier X prior to them contacting Tower. Runway 12 was in use so I built a hole for Air Carrier X intersecting runway departure from Runway 21L. I used TIPH (taxi in position and hold) with Air Carrier X on Runway 21L and was planning to launch them between two touch-and-go's on Runway 12. When I issued the takeoff clearance to Air Carrier X they started asking questions about what Ground Control had discussed with them regarding not flying the ODP. I answered the question and then they asked another one. They didn't start their take off roll until I cleared them for takeoff a second time. The Cessna on final for Runway 12 was on about 1/4 mile final when Air Carrier X passed through the intersection. PRC needs to come up with better procedures for IFR departures now that we are not allowed to say 'fly runway heading' without first playing 20 questions. In hind sight; I should have canceled the takeoff clearance and held Air Carrier X in position until all of their questions were completely answered. Also; I don't believe the flight crew should have waited until TIPH to start asking questions if they were unsure. Recommendation; [we need] better procedures for IFR departures. It is nearly impossible to give an IFR departing Runway 21L the ODP (immediate right turn to DRK) without Local 2 shutting down their pattern and holding out their arrivals. Develop SIDs for PRC.