No need to drill deep for light fixture. 1" depth should be fine I guess. The main concern is that you need to guess which way is the AC power line was routed to the lighting point. The standard practice is that the wire is laid in 0, 90, 180, 270 degree angle, not at odd like 45 degree.

Once you drill holes, put in suitable screw plugs and screw the light fixture. I thought the light fixtures normally come with their own screws. Any screw will do. If fixture need to be hooked, then use hook screw. If the fixture uses special bracket, just screw the bracket with normal screw.

I suppose you would be using round head metal type to go with screw plug

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When it collected dust, can you dipped it in water to clean it?

Why you need a light point when it is only weekend house?

Why not use it for sensor to alert you for something going on in front of the house?