Judging from what other people reported, the “original” Facebook app seems to cause a lot of trouble:
If you have this app installed, switching to some alternative implementation might make your experience a lot smoother.
Apart from that, as you haven’t indicated which version of the OS you’ve installed: You have updated your Fairphone OS to the most current release, right?
Your issue with the speaker seems like a hardware issue to me. Try to contact support about it, as this might still be covered by warranty.