Welcome! You've already been given good advice. Some of us mix many brands together and yes, it is easier to start with the harder brands and/or the pencils, and then use the softer brands for the finishing touches as the soft brands will deposit the pastel onto pastel already layed down on the paper, where the harder pastels may just "plow" through the pastel that is on your paper.
Lots of us store pastels in different ways. If you are just beginning, you might want to cover your finished pastel with some tracing paper. That's what I use. A more expensive way to cover them is with glassine. Now I tape my paper onto foam board and then cover, but I used to just tape the tracing paper to the paper and store in a portfolio. I would cut the tracing paper to the exact size of the paper, and tape to the back of the artwork.
You can get cheap tracing paper in rolls from Dick Blick or probably any art store: