I have a couple brand EIDE cards, sonnet being one of them, that are bootable. Never seen the point of using SATA on an old powermac so I have no experience with them.

I don't recommend and external USB DVD burner since most USB cards for old macs are USB 1.x and can't support the speed.

Firewire would be cool if you have a card that can support the power requirements (one in my beige G3's has a power connector to the card to drive an external drive). it seems firewire external enclosures are a bit rare these days.