welcome to the forums and lmde
most of the issues you are reporting will be "fixed" with the next respins where we will have separate cinnamon - mate isos
the current isos have both bundled because (my opinion) of historical reasons:
after UP4 with the arrival of gnome-shell to debian the inclusion of cinnamon in the isos (at the time still a young project) was the best answer available to gnome-shell;
but because cinnamon was still young and a radical change for the users that were updating from gnome2.x mate was also included as a more familiar and stable option.
today both projects are mature (this doesn't mean that they are not improved everyday) and deserve dedicated editions; that's what is going to happen later this year/beginning of next.