What is a good avg speed/cadence to maintain on this ride?
The one you maintain.
Look, one man's fast is another man's slow. It's going to depend how many hills you climb, how strong the headwind is, how many lights you stop for, and whether you're drafting a fit lady with well-toned leg muscles.
Average speed is only meaningful when you do the same course over and over and over and over and over again.