1 - I have that mini vase and it is Shawnee. I don't have a problem with the paint except is it fired on ? I do have a slight problem with the marking, it looks like the "S" is much larger than the U & A. If this is truly the case and not a glitch from the photography then it would be Brush McCoy.
3 - I have seen another Shawnee vase with a similiar glaze technique. It looks like either an end of day piece or a glaze testing piece. Either way, they are fun and unique. Obviously not a regular production piece.