Editor role rename: I re-tested just now with success and can not repeat the described problem. Can you look at the server logs for related PHP/MySQl error messages?
You have to revoke capability from all roles except ‘administrator’ in order it become available for deletion.
If role or capability available for deletion is not really deleted there would be a server side problem. I ask you do the same – check server logs. May be it will help to identify a reason.
If it’s possible, you may provide me access to your site (support [at-sign] role-editor.com). I will check what’s going wrong myself then.
If URE shows ‘edit_posts’ for custom post type, then such custom post type really use ‘edit_posts’ and some additional capability may be required to work with this custom post type. I may say more if I have access to your theme.