FEW CHANGES IN PHP SCRIPT

Hello, 1. We sell home decor the major concern is we know MRP (inc. tax) (ex. 2799), Unit Cost (Before Tax) (before tax) (ex. 1624.11) and sells price (inc. tax) (ex. 2520 giving 10% discount on MRP). In purchase we need discount to be calculated automatically when we put Unit Cost (Before Tax) but this is not there. 2. We need customize the invoice (Regualar A5 & thermal continuous) as we need MRP on it and discount on MRP for each product and selling price. Need separate table for GST (CGST + SGST) as we deal with 3 slab of GST. 3. We also need customize the product Label. We also need purchase price of product coded like 1 - K, 2 - D, 3 - U, 4 - G, 5 - M, 6 - B, 7 - S, 8 - L, 9 - V, 0 - O. 4. During purchase adding multiple products at once by selecting. 5. Bill renumbering (If a bill is deleted the sequence of the bill can be renumbered). 6. How to search bill by product. (If I have sold product XYZ from search it should sort out). And many more