Mary,
I appreciate you might not be fully informed, so I'll give you the benefit of the doubt rather than assume you're some journo out fishing...
1) Some witnesses mention that one of the aircraft performed a wingover shortly before the collision. Does this imply showing off? with insufficient lookout before performing maneuvers?
A properly performed wingover is a lookout manoeuver, not an aerobatic one. Not showing off in the slightest, it allows the best possible view into the area you're planning to perform aerobatics, particularly under wings and things like that. In other words, no - not showing off in the slightest, merely trying (unsuccessfully) to clear the airspace.
2) The structure of the Tutor canopy certainly offers an obstruction to the view. This requires an even more careful scan, many aircraft suffer from airframe blocking the view.
Yes, it does. That's why lookout is in the assessment criteria for every EFT syllabus trip, why it'a drilled into student and experienced pilots alike -- not just for safety but also because we're training these studes to be military operators of aircraft where seeing the bad guy first may be the difference between a war sortie completed and getting shot down. The EFT lookout scan as taught was pretty well validated by the report, furthermore there was evidence that it was being carried out as laid down according to the inquiry.
3) One of the pilots was wearing corrective lenses. I don't see mentioned if these were varifocals or not, varifocals screw up your peripheral vision.
Don't know on this one, someone else may have to comment, tho' I suspect aircrew corrective flying specs (administered by a Medical Officer, and checked annually) may well not be varifocals.
4) I cannot imagine that wearing a bonedome improves your field of view or makes it easier to look around.
Trust me, it has no impact whatsoever. You can't see any part of the helmet when you're wearing it, and it doesn't restrict movement in cockpit.
5) Should it not be part of the PIC's training to practice actually jettisoning a canopy -preferably on soft grass.
The motor memory part of locating the canopy emergency jettison handle had to be practiced monthly (IIRC) as part of the abandon drill when I last flew the Tutor. I doubt actually pushing the canopy off the rails would be of any use whatsoever; as the report suggests the hard part is finding the canopy handle in the first place.
6) Taking off together in close formation is a very military sort of thing to do, is the usual thing to carry on then flying near each other? Without a plan, or a qualified observer in radio contact with the other aircraft, this was asking for trouble. Formation flying, or ariel photography require special care. Flying kids around requires even greater care.
They took off a minute apart -- in no way whatsoever is that 'close formation'. Close formation takeoffs are done in echelon (or similar), even a stream take off (one behind the other) is done at no more than five seconds separation in the Tutor from what I remember. At climb speed, a minute's separation would put the aircraft over a mile apart in the climb.
To suggest, as I think you do, that these two pilots operated with anything other than the utmost care is, in my mind, pretty poor form.