This uses a rubber over the pan rail gasket correct?

If so, the amount of gasket compression is set by the odd shaped washers under the bolts. Screwdriver tight or just short of snapping off and gasket compression will be the same. (Unless the washers crush )

These are 6 mm threads correct? I'd go just tighter than a very hard to turn screwdriver. ( I'd have to look up a spec otherwise. )