Can I make a payment before my actual card arrives

Yes. There is no requirement that you even ever get a physical Apple Card. Many people use Apple Card with Apple Pay on their phones and never even order a physical card. You can pay on your phone as described in How to make Apple Card payments - Apple Support or you can pay online at https://card.apple.com/

Yes. You don't need the physical card to pay your account if your Apple Card is already active on your device.

Be aware that you can’t “pay-ahead” your apple card electronically as you can w/ most credit cards.

You can only pay “up to” the current “cleared” balance.