11x14 Frames, Display Pictures 8x10 With mat or 11x14 Prints Without Mat,Wall Mounting,Brown,6PCS

Package had a plastic envelope with 2 brass colored pieces and 7 plastic pieces with 3 pins sticking out, What are these?

I am interested in purchasing 31 sets of these 6-frame sets. Is that possible?

After peeling off the protective film, lettering from it is stuck to the plexiglass. What should I do?

What are the measurements of the mats? I want to make sure they wont cover the edges of my picture.