As for Right or Left to unclip first?...i get the whole theory of where the road is higher, etc...but, like anything else you will ever do...do what feels best and most natural! I was "taught" as a little girl to start up on slalom water skies with my right leg in the grip, drag the left...no way! That had to change and for the past 36 years, i ski with my left forward.
Do what feels best to you...that always! works!!!
: )
Just one more thought...i seem to be able to 'hover' at a near stand still without getting off my bike...not sure how, it just happens. but , that's a great thing to practice...you can unclip, hover for a minute to see what the situation is and then either get off the saddle adn wait or take off again.
ps...practice near grass!