I agree with the other comments, wait until you white wash, but I would be tempted to paint some colour of the walls if you cannot remove the trim (it might be there to tidy up the joins).

These tradies are cowboys . I have never seen a mess like that in a bath or else where in over 30 years . The bath normally sits on a bed of concrete slurry or if it is a cast iron bath it should be supported by either feet or the hob. The bath should have enough room under the edges to allow the tiles to go under the lip so a proper silicon seal can be applied all the way around the lip of the bath. As for the insulation it is not necessary to have it wrapped in any water proof protection. If the water is getting onto the insulation then you have bigger problems and from the look of the photos this looks like a definite future possibility.I like to put insulation batts all the way around the bath to try to retain the water temperature for as long as possible,not many people do this though ,but the more you insulate things the better. Looking at your photos the pipework connecting the waste is broken off so the hob will need to have atleast one side pulled off or an access hole cut into it to connect the plumbing. I would be getting these plumbers and builders checked out,if the photos are any indication to go by then there would be other areas of faulty workmanship for sure, -sorry to tell you.

No it's not too difficult it just needs a tradesman with some degree of scribing & finishing chops..that's so bad it's comical..... The portion of skirt under the lower step doesn't need to be profiled, rather it needs to read like the stair stringer detail has extended to the floor level and returned around the corner and abutting into the original larger skirt profile... Whatever you do on these things you don't want to notice anything and currently it's an eyesore Good luck! PD

R u laying boards over the concrete or beside?