Herewith my answers, sorry for the late reply but was on the road.
APs distance between one another: 40 to 65meters
Mesh: Yes we are really running a mesh. We've done a few installations in the past. There are two root APs and then another 4 APs. The other 4 APs all have 1 hop to their respective root AP. From the root APs there are CAT6 cables going to a PTP CPE that is connecting 500m away to a Sectorised Antennae. From the sectorised antennae it goes into a switch and breaks out to the internet/business servers, etc.
Smart OS: Unfortunately I am not on site anymore to login and confirm this