Hello, no it will not affect your 3.0 licenses as you can have multiple licenses tied to the same device, just don't try to run both programs at the same time on the same computer obviously and all should be good.
For a DAW MIDI trigger you will need the FULL version as EXPRESS does not come with MIDI functionality.
Everything new in 5.0 is listed on the product page for its description: https://www.adj.com/mydmx-5