Screed over uneven tile floor

No existing tiles would need to be removed , many thanks luke

I am a flooring footer and have screeded over floor tiles . You would have to prime floor 1st . Just make sur you get a good quality screed . Hope this helps

Screeding over floor tiles is fine. Mapei do a good primer.

All depends on how well the tiles are fixed to the floor, if they are well fixed i would use a degreaser, then use Ardex NA, it can be applied without a primer, for most other latex's i would use a Grip primer, this will give the latex a surface to bond to, do not use a normal primer as stated above. if the tiles are not stuck well then it all needs to come up, tiles and grout, so you have a nice clean surface to work with, always seek advice from the technical service provided by the screed/latex manufacturer, hope this helps, i could go further into it but you may become bored :), just seek proffesional floor layers help!! not builders!!!