Dear Student,
Uniform Circular Motion means that the angular speed is constant; but it would not be uniform if the angular acceleration was not zero (meaning that the angular velocity was changing).
Answer to your 2nd query is attached in the pic.
Regards,
Priya Agrawal.
![](https://s3mn.mnimgs.com/img/shared/content_ck_images/ck_5fc224a301cb7.png)