1) Is there a feature I can set on blockchain.info that will automatically sell any incoming bitcoin deposits to USD, and then transfer to my bank via their exchange Shapeshift?
2) Is there a feature on Coinbase I can set that will automatically transfer all referral payments to GDAX, and then sell to USD and transfer to my bank?
Not any that i'm aware of. Coinbase and blockchain.info are primarily designed for personal accounts and not designed for merchants or business accounts. There are better options out there for those needs like bitpay or coinpayments.
Another thing is, shapeshift that is incorporated into blockchain.info doesn't actually deal with fiat. It only deals with altcoins like ETH, XMR, and BTC itself.
What you can do though, is get an omni address, paste that into shapeshift.io, choose bitcoin to tether exchange and it should give you a bitcoin receiving address. Whatever funds that go into this address will automatically be exchanged to tether, which is supposed to be pegged to USD fiat at 1:1 rates. You can then sell the Tether for actual USD.
