InSAR vs. PolSAR techniques for Uninhabited Aerial Vehicle Synthetic Aperture Radar

Hi guys
I hope you are all having nice weekends

I have started to focus on POLISAR (the combination of POLSAR & INSAR). Can anybody help me understand:

1) What advantages of polSAR and inSAR are significant that we combine them?
2) In what applications, UAVSAR employs polSAR and/or inSAR?
3) what are the recent challenges / research focuses on polinSAR and UAVSAR?

any comment is highly appreciated
Thanks a lot, in advance!