I got the first 3 Ewoks only (Teebo 7*, Scout 5*, Elder 4*) and they are alot of fun. i use them in GW and Light missions together with Chewy (because he is like a huge ewok) and JC (because Elder's heal is weak and has a high cool down). I use them on an alt account only, so it will take like forever and 2 years to get all of them to 7* (incl. Chirpa) ... and sorry, no experience in using Chirpa at all! :(
Teebos leader ability can bring you in trouble (all hidden except healers = ouch), so i would go with Chripa leading (im sure additional turnmeter will help way more than random stealths) and would add any damage dealer to the team, because the scout alone takes too much time to kill the opponents.
You rather dont use them in arena ... half of them will be gone before their turn starts.
In GW they are great (fun).