Could I acquire a mixed DAEs for VNx5200?

Currenlty, our company has acquired VNx5200 with two 2U 25 DAEs in Sep 2015. We would like to enhance the storage system.

(1)   Could we add two DAEs with one 2U 25 DAE and one 3U 15 DAE?

(2)   Has the product already reached end of sales?