Hi Paul,
To answer your questions about whether there is a difference between "before I speak” and “before speaking”, I would say there is no difference in meaning. In terms of grammar "before I speak" is an adverbial clause, and "before speaking" would be a reduced adverbial clause (more like a phrase now). It is just simplified and therefore a good way to vary your sentences so that they don't become too repetative. I hope that helps.