You can use the same ticket system
, yes - click on PT4 and then on "Contact Us" in the bottom right.
To delete custom stats within PT4 you need to do them one at a time, yes. However, if you want to get rid of them all and start again you can do that by closing PT4 down and then deleting the following file:
Note that this will remove ALL custom stats, so if you have made any in PT4 that you want to keep you should export them before deleting the file so that you can re-import them.