1 - Can I include promotional materials for my store, when sending out Mana Pool orders?

Yes, Mana Pool has no prohibitions on including marketing materials for your store/business.

2 -  Why is the number of sales displayed on my shop and avatar less than my total sales?

The number of sales displayed only includes confirmed sales that have had the chance to be received by the customer.

If you click the linked sales number, it will display the Seller Profile. The Profile includes both the number of confirmed sales that matches the top level display, as well as a count of lifetime orders.

3 - How does sales tax work on Mana Pool?

Mana Pool, like other marketplaces, is required to collect and remit sales tax on orders - this is not the responsibility of the seller.

Buyers are charged sales tax on orders, and Mana Pool files sales tax returns and remits sales tax to states/regions.

Mana Pool currently collects and remits sales tax in about 15 different places. Each state/region has a threshold where a marketplace is required to pay sales tax (based on number of transactions and/or dollar volume), and Mana Pool adds new regions as thresholds are met.