Is there a minimum distance between the microinverter and the roof, as well as between the microinverter and the DualSun SPRING panel?

YES, a minimum distance must be respected as no element fixed on the rails, for example micro inverter or optimizer, must be in contact with the back side of the panel.

Therefore, a mechanical mounting element suitable for the rails of the mounting system should be used to fix the microinverter (or optimiser), if any, in such a way that a minimum distance of 19 mm between the roof and the microinverter (or optimiser) and 13 mm between the rear of the SPRING module and the top of the microinverter (or optimiser) is ensured. 

For example, an aluminium bracket with oblong holes can be used.

See mounting example below: