There are several options - depends how fancy you want to get.
Simple approach for beak - have a second layer with the beak open. Then put the closed beak and open beak layers in a "Swap Set" and put a trigger on the open beak with a keyboard key. Then when you press the key, the closed beak layer will disappear and the open peak will show.
If you want to have an intermediate from (smoother open/close of beak) have a look at the "Cycle Layers" behavior. You can make it so when you press a key it will display a few frames in a sequence to open the beak, then a few layers when you let go (in reverse order) to close the beak.
If you want lipsync (you talk, bird beak follows you) you can use the Mouth visemes. You might just tag the same open beak with all of the visemes (!) (normally for a person you draw different mouth positions for different sounds).
For the wings, you can do the same - just draw the intermediate frames. Cycle layers can loop for example. I used this to do a butterfly - I just draw all the intermediate positions and cycled through the layers.
But you can also do things like put a dragger on the wing (make it an independent layer so the wing movement does not affect the rest of the body). You can record dragging the wing so play it back several times. You need to think what sort of look you are after. Dragging just moves (and stretches) things. As soon as you want to show say the underside of the wing while flapping, then you need to use something like triggers or cycle layers (you have to replace the image, not just warp it).
For walking, you can use cycle layers again, but there is a "walk behavior" that might be useful. Set up the waist, hips, legs tags (forget the arms). I think that should work.
Check the user guide and intro videos - but terms to look for are "cycle layers", "triggers", "swap sets", and "walk behavior".