combining a familiar, special mount and animal companion

[Noxangelo]

is it possible? and more importantly, would it be worth it?

this includes things like the obtain familiar and wild cohort feats

[Elkad]

Sure.

Arcane Hierophant is AC+Familiar

You can get extreme with builds like
http://www.giantitp.com/forums/showthread.php?104367-The-Supermount-2-0-updated
or
http://www.giantitp.com/forums/showthread.php?142554-New-World-Record-Mount-Familiar-Companion-by-HD

[Psyren]

An Eidolon can fulfill all three roles.