1. I would recommend to use CRT extension or even batch from D365 instead of doing this from POS
2. This is not POS API, but google about 'open external app from Universal app (MPOS), from web app (CPOS)
3. What kind of discount? Manual one or some of retail discounts configured in F&O?
4. What kind of discount? Manual one or some of retail discounts configured in F&O?