@glensc So I asked our support / consultants about it column order. This is what I got back:
"it doesn't, as innodb doesn't do partial row reads (except blobs which can be stored entirely off page) so when you read col1 or col3, at the end you are reading row Y which contains col1,col2,col3,col4"
The comment from one of our senior support engineers is that on MyISAM it can make a small different with varchars / blob at the end of the table def. Int type order won't matter, put your most accessed columns first.