Yes, Envoy is still pretty much hiring ANYONE with, or close to having, the time to be a captain.

DFW is currently junior, but not a lot of difference between bases. MIA is slightly more senior. PHX, when it opens, is expected to go pretty senior.

As a DEC, you can expect to be on reserve for quite a while. Likely 18-24 months. Every single FO hired before you will continue to keep you on reserve as they upgrade. The only thing that will move you off reserve is enough new DECs hired behind you to move you up. I doubt if there are still enough DECs available to be hired to move you off reserve any time soon.