[}{arlequin]

I have no experience with the spare, but just in case, I'd inflate slowly, wear eye protection, and try to make my arms as long as I can.

As for the jack, although at first it seems unnatural, your initial idea was correct. Once you shove it in there, you'll see that the folding part has no way of folding down, regardless how it appears. The car itself provides leverage which in actuality pulls that little arm upwards towards its "stop." Try it and you'll see it makes sense.

The crank should be your first and final clue of how the jack should be positioned. As far as usage, although I wouldn't use it while crawling under the car, it's perfectly fine for a tire change. Unless someone is willing to have a floor jack with them at ALL times, what other option is there?