Big Pistons, dealing with the numbered items in your list in turn, I specifically asked what GPS training could be offered which would not be covered by conventional non GPS training.
1. These are normal flight planning considerations and not Specific to use of GPS.
2. So is this.
3. That will depend on each individual GPS unit. It is not realistic to train for the use of every conceivable type of unit.
4. Is it necessary to train for the blindingly obvious? (I.e don't take off with a flat battery in the GPS)
Not using out of date charts and data is part of normal flight planning as is ensuring a sensible flight plan.
5. Is it necessary to train someone where to place a portable unit in the cockpit? Different units and different cockpits will have different requirements which can only be assessed based on individual circumstances. Pilots must ultimately make their own minds up.
6. North up or track up is a personal choice and pilots and instructors will never agree on which is best. Which data to present on the screen is a good point but also often a matter of personal preference and the abilities of the individual unit itself. It is not possible to train for the use of all units.
7. This brings us back to normal non GPS flight planning again.
I don't decry navigation training in any way, but there is only so much specific training which can usefully be given for the use of GPS which would not have been covered in "normal" heading/distance/time/chart non GPS training. Pilots who have attentively taken on board normal navigation techniques should in most cases be perfectly capable of figuring out how to sensibly use a typical portable GPS unit using common sense and an instruction book. Complex built in aircraft specific systems like G1000 will obviously require specific software training whether by instruction manual. Face to face, video, simulator or whatever.