In the skin's skin.ini file under [Mania] there's on option called ColumnStart: make the number bigger to move it to the right, smaller to move it left. every key mode has its own column start option.
As for the right side column make sure you dont have a typo or something inside the skin.ini that correlates to that column
Hm. Not sure entirely, write your issue on the github: www.github.com/ppy/osu/discussions . Make sure to check to make sure there are no already open questions pertaining to your issue. There are a lot of issues right now with skinning as its not completely finished and osu!mania is definitely not complete.