Addresses and private keys are not the same thing in any coin. The private keys are why you lock down wallet.dat like fort knox. With them, you can take possession of any coins assigned to that account. Most exploits that have been successful involved stealing wallet.dat (or it's equivalent) and plugging it in to a new client. They are not the same length or format as the public key address.

That's general. I think these keys just alter the staking rate, if I understood correctly on other posts.
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Private keys are 256 bits long. That's 32 bytes, or 64 hex digits.

paycoind wants the PC key in a format that SetPrivKey() can parse. That's a 279 byte structure. Here's code that describes the structure. So the first 9 bytes are always exactly 308201130201010420, then there's 32 bytes of private key, then there's 173 fixed bytes a081a530[...]44034200 and finally there are 65 bytes of public key.

Note that the last 65 bytes (130 hex digits) are the public key, and they match the public keys in the paycoin source.

You can use the 'Wallet Details' tab at https://www.bitaddress.org/ to verify that the 32 bytes of private key do in fact correspond to the 130 bytes of public key for each pair.