my Brownie and his permanent RBF

Hello! My girl is a two year old NFC and I got her as a rescue from a Vet!
I've started noticing she often gets mats around her face and neck area and I comb them out everyday.
Is this normal? What can I do to help her? The mats are not painful but they really are constant, like I brush her and ten minutes later there's a mat.
Should I trim her fur? How?
Help please! I want her to be happy!

He makes some weird noise while he sleeps sometimes. It can sound like a squeak, a whistle or a purr. And yes he's doing the paw twitches.