I see a lightning bolt icon () next to certain usernames and store names. What does this mean?

Stores that enable both Instant Invoicing and Onsite Payment are considered Instant Checkout Stores and will appear in search results throughout BrickLink with a lightning bolt icon. You can find more stores that support Instant Checkout by selecting the option to filter stores by Instant Checkout support on the Wanted List Buy page, on all Catalog item pages, and on the Find Stores page.

When buyers are submitting payment through an instant checkout method, the order items are reserved for 10 minutes to allow time for processing. During this time, you will see the order on your Orders Received page in the "In Progress" tab. Please do not adjust your inventory during this time.

If payment is not successful after 10 minutes, the items will be released back to your store inventory. Also, if a buyer uses the back button on their browser before sending payment instead of the “Cancel and return to BrickLink” link on PayPal, the cart items that have a remaining quantity of 1 in stock will show as sold out. If that happens, please let the buyer know that they simply need to wait 10 minutes for the items to be released.

The shipping cost suggestion pop-up will only show for orders with a shipping method that's set-up for manual invoicing. The shipping method must also be set to show the estimated fees on your Orders Received page as a pop-up suggestion.

The columns for insurance, Additional Charge 1 (handling fee), and Additional Charge 2 (tracking fee) will be displayed if any of them are set to be auto-populated by instant invoicing / instant checkout or estimation for any order on your Orders Received page.

I am seeing a black pin () next to all orders on my Orders Received page. What is this and what does it mean?

A black pin is the default icon for shipping methods. You can change the icon inside each shipping method's settings. The icon that you set for each shipping method will show up on your Orders Received page but is not shown to buyers.