For (1) you could do merged-mining, as it costs practically nothing extra to miners.  But then you have to be careful to keep interests aligned - the new chain can't be competing with Bitcoin, and should in fact be seen as complementing it in some not insignificant way.

(2) could be addressed using identities that have a cost to create, and can be blacklisted if they are abusive.  E.g. https://en.bitcoin.it/wiki/Identity_protocol_v1, though I'd say just burn the coins in an OP_RETURN transaction, since the proposed announce-commit miner sacrifice scheme requires non-standard transactions.