Changing down I take my foot off the pedal, going up I don't. Keep the power going lol
As for starting off in 4th, I could be wrong but I think that is just a safety mechanism. e.g. If your on the freeway and your in Auto, and you need power to overtake etc, you can shift straight across from Drive into Manual shift. If it went into 1st it would not be a good thing at 100+ km/h.
I assume this is why it starts in 4th, just for safety sake.
I could be wrong, but I too pondered the same question.