As far as actions in combat are concerned, the quote you've included pretty much sums it up. A familiar can take any action that it is capable of other than the Attack action. This includes the Cast A Spell action, Dash, Disengage, Dodge, Help, Hide, Ready, Search, and Use an Object. Since familiars are monsters, they can also take any non-Attack action included in their statblock. (This mostly applies to the more powerful familiars available from the Warlock Pact of the Chain feature.)
Note that what exactly your familiar is capable of is up to your DM. For example, I would probably allow an intelligent lizard to scatter caltrops. An intelligent seahorse, on the other hand, I can't quite see administering potions. See also this 3.5 question for more information.
However, I believe you are slightly missing the point of a familiar - just like in previous editions, its primary purpose is utility, not combat. For example, my players have used a raven familiar as a messenger. They have also scouted out an entire cave complex before setting a single foot in it using a lizard familiar. And finally, (I'm actually still slightly annoyed about this), they effectively skipped a covert, stealthy adventure through creative use of the lizard.