Don't know about the strain on the car, but a friend left her nissan primera with the wheels at a severe angle and it got swiped by a hilux which almost knocked the wheel off, lots of suspension steering damage.

Make the target as small as possible.

I Wonder, does leaving a car like this all day/night put any strain on driveshafts, rubber boots, grommets, suspension parts, etc. ??

In a word, no! Cars are designed to allow for movement of the front wheels.

I also always back into a parking bay - that is because one cold wet winters day soon after I passed the driving test a child ran out behind my car as I backed out of a parkign bay - the child did not understand reversing lights and the rear window was misted up so impossible to see though (door mirrors wet and useless too).I think it is safer and should be mandatory for parking.

Getting back to the issue of front wheels, I always leave them at an angle - in some places it's mandatory to do so. If parked on an incline make sure your wheels are facing the kerb ... if your brakes fail the car will roll into the kerb, not the roadway (as one is told in San Francisco) - the second reason is to make harder for someone to jack up and tow, most unlikely I know, but with the rear wheels locked by the handbrake and front wheels facing sideways it gives the tower little option to work with. Does not have to be full lock, just a slight turn will do the job. As for strain on the mechanicals, I've never experienced that in over 30 years of driving - and car serviced by main dealer who I am sure would not hesitate to specifiy necessary work if required.