How do I tile over a leveled floor with a feathered edge?
You can easily knock down any irregularity with an angle grinder and a masonry blade. It will generate a lot of dust, so you'll need some good eye protection and good mask. 

The answer to your question depends on how planar the surface is and what size of tile you are planning on using. Bigger tile requires a surface that is more planar, while smaller tile can deal with a less planar surface.

Hope that helps.