As for matching your bank transactions to the transactions you already recorded in your QuickBooks Online, take a look at this article: Match and categorize bank transactions in QuickBooks Online. You can find the steps on how you can exclude transactions under the Exclude personal or duplicate transactions link.
Feel free to post a question below if you have anything else in mind. I'll be sure to get back to you.
freight paid by the customer is income, typically I post that freight income to its own account called pre-paid shipping. The freight you pay is either part of the inventory item cost, or an expense if you are not buying inventory.
Which account gets posted to is determined by the item you use on the invoice, typically for this you would use a service item linked to the income account, pre-paid shipping