From what I've observed of their operations at Cardiff each based aircraft tends to average 4 departures a day Monday to Friday and 3 on Saturday and Sunday. It looks like each aircraft has 2 crews assigned to it everyday. 1 for the morning and 1 for the evening. Whether that's typical for Flybe operations or unique to Cardiff i don't know.
I believe that Flybe keep 4 Q400s and an e jet on the ground every day as fleet backup .