Prepare walls for painting - fill and sand?

[OxyOni]

We want to have a go at smoothing the walls in one room for painting. The walls have some imperfections like fine cracks, small openings at the corners and other imperfections, as you can see in the attached photos.
Could we make these walls good for painting without skimming them? Would fill and sand work?
We want to fill any imperfections and sand it to a fine finish.
Could you please give us any tips and recommendations?
What filler should we use? (eg Toupret Easy fill?)
What sanding paper grid? What can we use to avoid dust as much as possible but without costing a fortune?
What to put on the walls before painting? Anything else before a mist coat? Would anything come through the paint?
Would it be a very big headache to do it?

Anything else that you want to add that could help us?
Thank you.

 

[Wayners]

Scrape out cracks to allow for toupret powder filler.
120grade sandpaper.
Bodge a cheap orbital sander on a vacuum to sand.
You can fill over the entire wall with toupret powder filler. I prefer that one.

Not that easy Vs skimming as time consuming.
Result can be mixed just filling and sanding depending on skill and effort.

Some paints need a primer. Some are self primimg. Depends.

 

[robinbanks]

What can we use to avoid dust as much as possible but without costing a fortune?

If you're using mechanical assist like a palm sander, buy a length of vacuum hose to extend your existing vacuum cleaner pipe and attach it to the sander's dust output port. Ensure you run with the vac on when sanding, and wear a mask too

 

[Koolpc]

If the walls are really bad, a skim would be easier.