No, if it were "descendentes de protestantes" the wording would be "of Protestant descent" as in "somone of Italian/Chinese/Japanese descent, etc".
To the second question, no too. "Several dissenting protestants" would mean discordante/divergente" (in Portuguese), because they were the ones that wanted a reform in a number of specific practices within the Catholic Church (and by extension we can safely say, the England Church - the Chatolic England Church.)
Their "protest" here would mean that they wanted some practices reformed, not that they wished to found new denominations, even though many of them left the Church many didn´t. And at the last, some practices were reformed and some even supressed (the selling of indulgences for example, and the Bible in Latin, etc.)
Anyway, since at the time they arrived to America many were already from new denominations (so not only divergence or reform anymore) some authors translate it as "protestantes dissidentes". It describe the ones that wished a reform within the church practices, but with time it came to mean any groups protesting Roman Catholic orthodoxy
at the time.https://en.wikipedia.org/wiki/Religion_ ... ted_Stateshttp://www.u-s-history.com/pages/h1136.html
They couldn´t be "dissidentes de protestantes" as well, since the Protest Reformation had just taken place.