David, use search from the main page it will return hits for the different topics.

Platinum Prints are paper coated with Platinum or a Platinum/Palladium mix (these are had coated papers - done by mixing up plt/pd and then spreading the coating onto paper - see Bostick and Sullivan for supplies)

Palladium like Platinum, except using only Palladium

Carbon, I do not have any experience with these - see B&S site for info.