Make modifications to POS software in C#

Have a look at the software at the link [login to view URL] , I will purchase this software for you and you need to make the following modifications to the software: 1) Individual items discount option (Should also be visible on receipt) 2) Products quantity in decimal numbers 3) Product expiry date alerts 4) When we select a category only those items should display which are from that category not the products which don't belong to the selected category. 5) Per liter, meter , kg addition 6) Improvement in Bar code reading ability ( currently not so good ) e 7) Bar code generation ability 8) Better Solution for editing or changing the prices of multiple products of same category or different category. 9) Better Search option , currently its not so good product search needs a lot of improvements. 10) Automated System for managing Clients who work credit. They should be searchable by name, date , address & mobile no. etc. 11) Alerts should be generated by the software when a client's credit date becomes due and alert should appear every day unless dues are cleared by filling in the required filed in the software. 12) There should be an option for putting Client's name, address & mobile no. on the Receipt. 13) New Fields related expenses should be included in the Software which should include daily expenses, utility bills , rent , salaries & other expenses fields. 14) Expenses should automatically be subtracted from the profit generated. 15) Complete inventory Solution 16) Graphical representation of best selling & low selling products weekly,monthly & yearly. C# Coding should be clearly understandable by using Comments options for explaining each and every section of the code. You have to provide complete source code. Payments will be made in 5 milestones and last 2 milestones will be released only once I test out the software for at least 2 weeks.