Hi Mastan,
For deletion flag, check in AFPO. For order status, check in JEST table using OBJNR that you can get from AUFK table. Search in this forum. There are many threads about order status table.
In RESB, you can summarize the required quantity to get the total requirement. "261" and "531" are the actual goods movements/consumptions.
For point 2, how do you know which stock is reserved by a sales order? If there is no direct relation between the sales order and the stock, you can use the above logic.
Regards,
Julian