I have tried those bruhses, but the work I do does not call for them too much.. They are beautiful brushes though.
I do not remember the brand name of the gouache I use. I love it's brightnes though
as far as oils, it is just easier to frame and sell oils than it is to frame and mount 4 foot long watercolor paintings, or 6 fopot long drawings.
it also allows for easier storage once the oils are dry.