Update and delete entry in Datasheet via Userform

Hi,

I have a userform for entering new data in to a data sheet. This userform also has a listbox with items already listed in the sheet. Basically it is divided into two frames whith the form with all the input boxes in the frame to the left (see below). The user can either add completely new data or pick one from the list as a "template" or so and ammend.
There are two remaining issues that I am struggeling with:
1. How to choose an item from the list and update it so that it replaces the excisting data.
2. How to delete an item - in other words blank out the data for this entry.

Help is much appreciated.

Userform.jpg

Here you go...
Book1.xlsm