Advice for our first Shopify mobile app project (shipping, catalogues, customer role and NAV erp)

[Dido_Quamm]

Hello!
We're working on our first Shopify project and it we'll be a mobile App.
So I have a few questions:

• If a product in the cart can't be shipped to a selected region, can we block the cart or remove the product at checkout?
  Or is it possible to display an alert?
• Can we adjust the cart's total price to offer a discount for specific payment methods?
  Alternatively, could be an idea to dynamically add or remove a coupon based on a preselected condition ((es. I ask before the payment method I'll use))?
  But built-in option for this would be ideal.
• Is it possible to create multiple catalogues or set different prices for a product based on customer roles (like VIP customers), without using the B2B option?
  I found plugins like Wholesale Pricing Discount https://apps.shopify.com/wholesale-pricing-discount?utm_campaign=Guru+Ask&utm_medium=Forum&utm_sourc....

Also, has anyone had experience integrating Microsoft NAV ERP with Shopify?

Thanks for your help and kind regards,
Davide