Re to the OP:


Bitshares will have privacy with Bitshares 2.0 (can be enabled or disabled within the wallet) too https://bitsharestalk.org/index.php?topic=17687.30 (see the whole thread).

Ethereum's proposal for POS is casper. See https://blog.ethereum.org/2015/08/01/introducing-casper-friendly-ghost/
Review by D. Larimer http://bytemaster.github.io/2015/08/08/Review-of-Casper-Ethereums-proposed-Proof-of-Stake-Algorithm/

Bitassets are backed by Bitshares not by themselves. And Bitshares (BTS) have value apart from being a collateral for Bitassets. BTS is the core asset of a platform that supports many use cases besides Bitassets.