Having a bit of experience starting minis in extreme cold, I find the drag from the few moving parts in the transmission to be negligible.

Once running, a properly set up clutch experiences no undue wear or stress when you are sitting at a light with the clutch disengaged. In situations where it makes sense, I gladly hold the mini on an incline with the clutch.  

You've answered your own question...

The thrust washers are dribble fed by leakage from the centre main bearing, not pressure fed.  Cranking with your foot on the clutch means that the full pressure of the clutch is bearing down on an unlubricated surface.  It's got nothing to do with making the starter work harder, and all about making your engine last longer.

Frankly, if you're stupic enough to start ANY car without checking it's in neutral, then you deserve to go through the back of a garage.

I don't get the "foot off the clutch while starting" one. Maybe because it puts pressure on the thrust bearings increasing cranking resistance, but there's a lot more resistance when the transmission oil is at -20 C or -30 C....
I'd think the safety issue of not putting the car through the end of the garage is more important.

At traffic lights, the pressure on the flywheel resulting from the depressed clutch pedal places load on the thrust washers, causing them to wear. But is it more significant in an A-series than any other motor with a clutch?

Clutchless shifting (up or down... I can go from 1st up through the gears to 4th and back down) is a useful skill when your clutch mechanism packs it in (had it happen on a Suzuki Samurai), but, in my opinion is not a good idea for general driving. Synchros are relatively small but expensive parts, intended to help a gear match tooth speed and alignment with another gear, but they do wear. They keep the ends of the gear teeth from being worn. Clutches are much easier and cheaper to replace. In past threads (many, many years ago ) there was a discussion of the relative merits of engine braking, and a wise expert (it may have been Kieth Calver) advised that brake pads are far cheaper and easier to replace than a clutch. In other words, choose your form of abuse carefully.

I have come across several comments on some things not to do clutch wise with a mini, such as don't start the engine with the clutch depressed, don't ride the clutch at a stop light. I wondered if there are more good tips out there. Out of habit, I often speed match to go from 4th to neutral when coming to a stop, clutch-less, is this bad form when done cleanly, or not forced?  in my case this is a pre-verto with rod change 4 syncro trans, all working very well.