As far as I can tell, people only do Fleckerls in the way that lets them use a Contra Check to change. So the basic pattern would be Reverse Turns from the edge to the center, Reverse Fleckerls, Contra Check, Natural Fleckerls, Natural Turns to the outside again to resume travelling around the floor. I don't think I've ever seen it go the other way around, probably because there is no similarly good switch from a Natural Fleckerl to a Reverse Fleckerl. I'm sure the syllabus has a couple follows for each step, but Fleckerls always seem to be done the same way.

Speed up/slow down -- it's possible I guess. I haven't watched high level ballroom dancing in some time and can't remember what it looks like. They should be pretty close to on time at least, but it is possible that the dancers will speed up a little bit to account for the time it will take them to get started again, coming out of the Fleckerls into regular turns. Kind of like how starting the dance from a full stop can take a little time to speed up to match the beat; they could want a little extra time to adjust from the fast spins to the slower turns.