Help on a Excel file

Hi,
I need following help on a excel file:
The excel file is an economical evaluation to compare two products. Unfortunately the file is in German but it is more or less self-explaining. I have also attached an word file with the englisch names for the input parameters.

I would like to implement following features:
- Select right currency (Wirtschaftlichkeitsvergl.! B6): list of currencys in sheet “Referenzen”; the problem is that the list always gets lost after saving the file
- Change currency format into the right currency (sheet “Detailberechnung”) when selecting the currency (Wirtschaftlichkeitsvergl.! B6)
- Calculate the break-even point / amortisation time (years) in following diagrams (Gesamtkostenvergleich & Komulierte Barwerte); I want to have the number (in Detailberechnung!B79) and if possible also indicated in the diagrams
Can you please indicate how much time you need for the adaptions? Furthermore, do I get an official invoice?

Best regards,
Clemens