Floor around toilet
The area around the flange is not a problem because the toilet will cover a fairly large area. Just make sure the tiles (even the small piece) are pressed firmly into the adhesive so that there is no movement. If all tiles are snug against the sub-floor you shouldn't have any issues. As to where the tiles meet the threshold, gringing provides a cleaner edge. It can be a little tricky and leave you with edges that don't have the same ground contour. You might consider a transition piece. This is a strip of metal, wood, vinyl, or other material that covers the tile and whatever flooring it meets with. Transition pieces vary in style and shapes but are designed for this purpose. They can accomadate flooring of the same or different levels, that is why they are called transition pieces.
Hope this helps.