A vast majority of transactions don't need to wait for a full confirmation, simply existing in the mempool is enough. Just like my electric bill doesn't need to wait for the ACH transfer to complete before it's considered paid.
And I'll note that there are other ways to accept bitcoin payments without high fees or long wait times (lightning).
2. Chargebacks are disputed, and as a storefront you can prove that you are not liable. Merchants can review the identifying documents of the cardholder for legitimacy and take other security steps, like using a chip-enabled card terminal, to further confirm the validity of the purchase. If they follow the process correctly, they are not liable for fraudulent purchases, the cardholder’s issuing bank is. Visa and MasterCard’s contracts generally put the burden of fraud reimbursement onto the bank.