Expenses, Online Banking, Credit Cards

1. If these really were expenses and not inventory parts, then you need to input the payment (check, credit card, whatever) as of the date you made it.
2. You track your expenses in QuickBooks. Online Banking just downloads transactions. I think it's better to enter your transactions (allocating them to proper expense and other accounts) and then match them when you download, but some users prefer to wait for the download process.
3. Your business credit card is set up in QB as an account, much like a bank account. When you reconcile the credit card statement, you'll be given an opportunity either to create a payment check right then or to create a vendor bill for later payment.

I encourage you to download the QB 2010 for Mac user's guide (assuming that that's your version; you didn't select one when starting this discussion) and check out the information it provides. Use Help (menu) > User's Guide. The first time you'll be guided through the download; after that, the command should open the guide.