Get your border drawn out. Then dry lay the centre so you are happy with the cuts.
Then glue down approx 1m2 in the centre and make sure it’s tight. Once that sets you can’t run out.
Use f48 plus adhesive if possible as it’s high temp so good if any sunlight.
That’s good. But free 25 years they perish.
But anyway.
You need to get as much up as possible. Then do a full coat of ardex NA / fball 1200 / or similar
That looks like you have moisture suppressant on it. But needs to be an epoxy one.
Without seeing it I’d say you need to take it all up and remove as much of the compound as possible.
Does the floor have a damp proof membrane ? How old is it? Before 1980 ?
Are they proper carpet fitters. Never know any who would let a customer do the grippers.
The distance is usually 4-7mm depending on the thickness of the carpet. The whole point is to trap the carpet against the skirting.
Could do with a new twin doortrim. To be honest ring a local carpet fitter. Prob cost £30-40 to sort it amd he would use a knee kicker to fit it correctly
Yes bricks in the floor. Kitchen can go in yes. Just make sure only the plastic legs touch the floor.
You don’t want any end panels touching the screed
The whole floor. The bricks need removing 1st then filling in with na and granno with a Dpm sheet ( visqueen )
Then na up to the new screed. How long has that been down?
What flooring you having ?