The screws and plugs are not included. You need 3 pieces. The lamp itself is not that heavy. I used 5x25 wall plugs and 4x25 (4x20 would also work) screws with pan head.

Another tip: when mounting, make sure that the power cables do not come to rest in the eyelets of the wire ropes. This happened to me, resulting in a short circuit.

As far as I remember, dowels and screws were included

Can no longer say exactly. But relatively small (a few mm) in our concrete ceiling. It also has washers so that small heads don't slip through the hole in the lamp.

Customised as required.