You will be able to complete 3 heroic adventures per day. however, if you complete a particular heroic adventure (usually with the powerful engram) you will have to wait for the next reset. As soon as that happens, they will again be available to you, and you can run through those heroics again.

Can you farm heroic adventures?

Players can start farming the TBM Heroic Adventures as low as level 75 since they scale to match your group's level... ... The order that the Heroic Adventures are listed in I believe is also the best order for doing them.

Can you do the same heroic adventures for Wayfarer?

No, they don't. You have to wait for locations becoming flashpoint to complete the heroic adventures for wayfarer.