Would agree with thedec Kevin.
On the whole, this looks fairly easy to get back up together and if I can just throw in a couple of things, hope you don't mind.
First off, washing the walls to get rid of the paper paste is without doubt 1st job and it can take a fair bit of washing to get it off, but hey ho, its only washing!
For the next part, I have found painting over with a thinned coat of 'supermatt' or other vinyl free paint, a good first coat as it does not react with any of the water paste residue you may have left on the wall. Let it dry for at least 12 hours, overnight is best, then give the walls a quick sand over.
Next up is the filler. Now we all have our own ideas on this, but I really do find that 'toupret' make the best powder filler. ( I don't like their ready mix, takes too long to dry.) Their Interior, or TX110 quick drying, is perfect and I give my reasons as, you can use this between coats of paint, great for this job, it's dry in about a half hour or so, it is very smooth and easy to skim over with a 3" or 4" filling knife and it drys out very white. I do not ask for more from a filler!
Not available everywhere over the counter, but as I use a lot all year round, I order the 5kg bags over the internet.
Red Devil lightweight, is also good and I buy that too, but it is not so good between coats of paint.
I stopped using Poly****** and tetr*** about 4 years ago.
Skim over your walls with the filler, let it dry, light skim again over any low areas or bits you missed, let it dry then sand off
Now I would then go back over with a second coat of Supermatt to cover everything and let that dry. De-nib, then apply your 2 coats of the vinyl paint in any chosen colour.
Seems like a lot of work but this should give you a pretty good finish
