B767 Captain experiences a gear disagree EICAS message after gear retraction. QRH is not helpful so the gear is cycled with positive results. Attempting to climb; the MCP will not accept any altitude above 9;900 and autopilot; autothrottle; and flight director will not engage. Flight returns to departure airport.

Narrative

After takeoff we received a gear disagree EICAS message with Gear Lever in UP position. Not a whole lot of guidance in the QRH for that. In fact I'm going to suggest some changes in wording for that non-normal. Anyway recycled gear and everything worked normally. Told ATC we were ready to climb. Issued clearance to 12;000 and when we tried to set the new altitude in the MCP; it would only go to 9;900 and then it would go back to 00;000. Any selection from 0 to 9;900 worked; nothing else did. Autopilot; autothrottles and flight director did not know what altitude was set and would not engage in any pitch mode except V/S. [We] returned to field under maximum landing weight. Total block time was about 1 hour. We were now illegal to fly our trip. Our day was terminated and scheduling sent us back to the hotel. I heard a common theme from Maintenance staff and others. The aircraft fly so much during the summer schedule there is no time to work on airplanes. This worked significantly against on time performance and customer satisfaction on this trip. First Officer and cabin crew were excellent in performance and attitude. Maintenance staff was also excellent in attempting to solve problems but apparently are presently overwhelmed by volume.