Make Userform Show Data From Spreadsheet And Add Delete Or Make New Entry

I have a spreadsheet on sheet 1 with a list of customers and their information. So on column A I have the customer number (i.e. k968, e37, p528,...), on column B i have the customer's name, on column C the street's name, on Column D the house number, on column E the zip code and finally the city on column F.

Right now there are around 600 customers in this list.

I have made a userform with a combobox in which I want to select an existing customer (pulled from the spreadsheet). On the same userform I have textboxes (customer number, name, street, number, zip, city). When I select a customer in the combobox, I want this customer's info to show up in the textboxes. I want to be able to change the info and hit Next to store the changes in the spreadsheet. When I do not select a customer from the combobox, I want to add new info in the textboxes and hit Next to store this info as a new customer. The userform also has a delete button. Then I select a customer in the combobox, this customer (and it's info) should be deleted from the spreadsheet when i hit Delete. So the spreadsheet is variable in length.