Hi,
1/ If the user is using the same address for the billing and the shipping ; by editing one, it will affect the other, because they are the same.
The customer need to create a new address if he do not want to modify the address.
So I don't see something to fix because the current process is following his logic.
2/ If you do not want update your product stock, you need to set an unlimited stock for your products.
HikaShop will update the product stock when the order is created or when the order is confirmed (depending the setting you used), but in all cases the stock will be update (unless you do not use any confirm status).
You can see to use a product custom field (require at least HikaShop essential) to store your "product stock" in a value which won't be affect by the HikaShop workflow ; it is a possible solution.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.