More information will be added to the OP to reflect answers to questions and to provide more information about how things have been progressing so far.
Any staking rewards up to this point have been allocated for bounties and other rewards. Surplus PIE is used to further development of PIE and related technologies.
PIE that is staking at POSWallet is likely bounty recipients who are now staking. We do not have any PIE in POSWallet.