1. Does this plugin work with the EDD front end submission plugin?
Yes, but you have to purchase EDD FES separately.
2. Will this plugin work in a multistore EDD installation? So multiple vendors can post on the front end their services?
Yes multiple vendors can post their service
3. Is it possible to sell services and digital products on the same installation?
4. Where do you see the reviews?
On particular order conversation page and on the single product page (if the option is enabled from backend by admin).