I accidentally paid for some medical expenses using my normal credit card instead of my HSA account. Can I withdraw the equivalent amount from my HSA without tax liabilities?
Yes you can. You will need proof of receipt for the amount and submit it to the bank who operates your HSA account. You have to ensure that your medical expenses qualify as they would if you had paid with your HSA account.
Yes, you certainly can. As long as you incurred the expense while you had the HSA account in place, you can pay for the expense in any way you please, and reimburse yourself later for that expense out of your HSA.
Just ask your bank/HSA custodian how to handle it, as the procedure is different with different institutions. With some, it is as simple as requesting a cash withdrawal. Others may have a form for you to fill out. Make sure you save the receipt/invoice. (Of course, you should be saving all medical expense transaction records, even those that you pay directly out of the HSA.)