How good do I have to make my walls before plasterer arrives?

[NiceNormalPerson]

Part of a 3 room overhaul involving moving plumbing, electrics etc. Our kitchen fitting people/ builder are over seeing all 3 rooms and bringing in a plasterer.
We have stripped living room walls of wall paper and underneath there is magnolia paint but in places it's lifted off leaving the wall patchy. We have removed all the loose flaky bits. Also there are some deep holes- especially around the window where it looks like lots of curtain tracks and tie backs have been attached in the past. There are also a few gouges maybe 7 or 8cm wide and 4 to 5cm deep in the walls.

My questions are:
How good do we need to make the walls?
Do we need to fill the holes and sand down best we can?
Do we need to remove the rawlplugs?

We have time to do this and will be paying plasterer direct so could save money if it's needed to be done by doing the filling rtc ourselves. It's just we have never had plastering done before so no idea how much plastering actually covers up or what's needed to be done before.

How good do we need to make the walls?
Not very. It is a good idea to remove loose stuff and especially paper, just in case the plasterer is not very painstaking.

Do we need to fill the holes and sand down best we can?
No

Do we need to remove the rawlplugs?
No, this is liable to loosen the plaster or make a crater. you should punch them in. Put a screw into the hole in the plasplug, tap it lightly with a small hammer until it sinks slightly below the surface of the wall. Then use a screwdriver to remove the screw from the plug. BTW when you drill and plug a wall, you should always do this so the plug is just below the surface. It reduces risk of cracking, and makes future filling much easier.

Brilliant. Thank you PigletJohn