Tony, good thinking.
Restrictions:- These can be identified by eye and using common sense.
Oil Coolers:- An advantage on any engine often running or expected to run, at or close to maximum power. The lubricating oil constitutes a direct method of reducing temperature in the bearings and the bottom end in general. Normally the sump/pan serves this purpose.
1&2. The actual figures are not important, but could br useful guide lines. The objective will be to simply make improvements, whatever.
Cheers, (Home brew in hand at this moment.
) Trevor.