Hi @landasamuel,
A warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.
For the chased-out sections leading away from your light switches, apply Hardwall Plaster mixed with hydrated lime to fill the void. Allow it to dry, then use mesh tape to reinforce the join on each side of the void, then apply a thin second coat to cover the tape. Use a 6" Plasterboard Joint Knife to apply the plaster and apply it around 10cm wide of the tape on each side, feathering it away from the centre so that the outside edges blend into the surrounding wall seamlessly. You can then scrape and sand the plaster smooth. If done well, you won't need to apply a topping compound, but if you can't get it perfectly smooth, a topcoat of Gyprock Less Mess Topping Compound can be added to make it perfect before painting.
For the ceiling patch, you should remove the plastic fixings and then clean up the surface with a sanding sponge. Once tidied up, use a Pfeiffer Plaster Repair Wall Patch to cover the holes, then apply Gyprock CSR Less Mess Topping Compound over the patch to conceal it. Once dry, sand your patch smooth and paint.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
