User Activity

Hi everybody, I have been trading on e-bay for a number of years and I now have the time to open a shop (yippee). I am wondering if I will loose all my feedback etc that I have gained over the years - or if I keep the same username will I be able to ...
As a seller I have payment instructions that are automatically generated on invoices. I have now made changes to my banking and need to change the payment details, for some reason I can not seem to find how to do this.