Shower - Can you screed directly over this?

Hi guys
Cutting a long story short, our bathroom shower was leaking and after a lot of argy-bargy with the bathroom renovation company, they have finally started re-doing our bathroom and shower floor.

They have agreed to redo the entire bathroom floor and the first row of wall tiles.

So far they have stripped back the floor (scyon board) and first row of wall tiles to the original membrane, see photos here:

https://imgur.com/a/QjnpwHC

They are planning to apply the following, in this order (based on my request that they waterproof over the screed and not under):

1. Primer applied directly to stripped back floor (as per above photo link)
2. apply a slurry (cement mixed with water and bondcrete) so that the screed will bond with the existing floor surface.
3. sand & cement screed
4. apply 2 coats of epoxy based primer
5. apply 3 coats of Water Based Undertile Waterproofing Membrane

My questions:

1. does the above process sound right?

2. Can they apply primer, a slurry and screed to the floor in its current state (its gritty, uneven with exisitng patches of orginal screed in some cases 10mm high)?

3. in the process of removing the first row of tiles they have inevitably torn parts of the 6mm villaboard lining the wall. they told me they dont need to replace this and they can just patch it. but this doesnt sound right at all. there are holes in it and its lost some of its layers from where the tiles have been pulled off. I assume they will need to cut out the damaged villaboard and replace it?

4. Do they need to redo the shower water stops? Is it the waterproofer who installs these?

5. as per the photos i've uploaded, is that a puddle flange? it appears to be one but with no drainage detail and the 100mm downpipe just sits inside it. The waste had a 100mm drain grate sitting directly on top of the 100mm down pipe with no gap for the screed to drain.

thanks in advance