To get your Facebook Pixel ID, please go to your Facebook Ads Manager Account, then from the Navigation Bar select "Events Manager". Under "default pixel" click "Settings" here you will find Pixel ID.  

One Pixel can be attached to unlimited websites. However, in order to be able to raise the pixel to be smarter and better optimized for advertising in specific areas/niches, you should use one pixel for a website specific to that niche (or websites with the same theme).  

You can test by installing the Facebook Pixel Helper extension on your chrome browser as it validates all your Facebook events on different pages of your website

Yes, Magento 2 Customer Discount allows you to set the page title and URL identifier of a dedicated page of special prices.  

Yes, Magento 2 Customer Discount allows you to set a particular price for multiple products.  

Yes, with Magento 2 Customer Discount Extension, Admin can apply promotion rules with/without coupon code.  

The most common pricing strategies are: Cost-plus pricing, Market-based pricing, Consumer-based pricing, Dynamic pricing, Differentiation pricing  

With this module, the admin can create rules using order attributes as well as Customer attributes.  

With Magento 2 Promotion extension installed on the store, customers can apply/edit/cancel discounts from a cart as well as the checkout page.  

Yes, you totally can do. You can set the default duration for a membership level from Manage Membership section. In case a membership level has different durations, go to the Product > select Membership package > set duration as Custom > add different durations.