1. De-mail it in the preferences.
2. STFU notifications, then carefully tune back in.
3. The feed is crap. Do not read the feed. Make a bookmark bar:
3.1 https://companyname.facebook.com/chat/t/<..> Chat link
3.2 https://companyname.facebook.com/notifications/hub/all/ Notification hub link
3.3 https://companyname.facebook.com/?sk=h_chr Feed, force-chronological order, for hard cases only
3.4 https://companyname.facebook.com/profile.php?id=<your id here> Link to your profile, to write notes et al
3.5 https://companyname.facebook.com/groups/?category=membership Group Overview. This is your cockpit, basically
3.6 https://companyname.facebook.com/saved Saved Posts. Because their search is crap.