Often when you have mould like that there is a lack of insulation above ceiling.
This causes ceiling to become cold in the winter months and the hot moisture in the steam or damp towels etc settles on ceiling causing mould.
Have a look at the insulation above and add more if required.
If you...
I'm no expert but I say the same as slabs.
Keep it's same height.
You could throw a handful of cement around the drain area in sand as that will help stop any movement.
Worst case you lift slabs and level again as not difficult to fix if its a problem.
Don't worry about it.
Normal.
Mt gravel drive had a huge puddle yesterday with the rain.
I'm lying new patio and where I dug out on the clay, it was like a pond last year.
Chucked gravel over then I'll layed slabs.
That's a low point and water runs to it.
You probably have solid ground so...
2kg box of toupret.
Do it in 2+ goes giving it an hour or so for first mix to set a bit so it don't slump out.
Try not to mix more than you need or you will be throwing away good filler
Oddly. And it's true.
Mods aren't here as much as some of us.
I mod a site and I can go days without looking so I think it's down to exposure.
If you hit ignore after reporting the post, it disappears so that's the best thing to do.
I don't think you will move that.
I've got several patio slabs on a plank ATM so they don't scratch the new slabs under.
The plank is a bit twisted and the slabs have made no difference even with the weight
I hired a pump for the 4 days before inspection.
Sun came out and dried it mostly before concrete.
Not a problem but was stressful when it was hammering it down.
I got the wrong type of pump as well and couldn't get it to prime in the shallow water so had to swap it.
Use a polymer like CT1 or Stixall.
Fill
Use waterbased paint over as a primer or topcoat. You have to use waterbased over first!
Use multi solve to clean up if you make mistakes