Several integration difficulties

Please help me in solving the following problems that occurs when preparing integration POS api to Deliverect Api:

Busy mode (open/close location) on https://frontend.staging.deliverect.com doesnt work. Click "close store" does not change anything, the same as chage it from our API. There is an operation success, but location status is not changed,
I cannot test configure tables for eat in (no such option available at https://frontend.staging.deliverect.com). According to: https://support.deliverect.com/hc/en-us/articles/4406618548753-Deliverect-Online-Ordering-Configure-Tables-for-Eating-In Is there another way to test Sync Tables in staging environment?
How to apply discount to specific articles (display on ordering channel as crossed out old price and new price side by side)?
Send test order from https://frontend.staging.deliverect.com/ and use channelLinkId as secret for create HMAC header as suggested here does not work: https://developers.deliverect.com/reference/hmac-authentication . What is the correct secret?
Register POS - the same problem as above. What is the correct value of secret?
When place order from https://frontend.staging.deliverect.com (POS API - partner webhooks - order notification) with entered customer phone number results in order that comes to POS api without customer.phoneNumber value. Is this bug or customer phone number is passed to POS api in another way?