1 - Yes, once you get the TradeFortress BTC you can remove the trust line to him, and you will still hold 1 TradeFortressBTC. If you ever send bitcoins to somebody who trusts TradeFortress, the client will use the TradeFortressBTC before using BTC from issuers you still trust.
Is there some Ripple address maybe some throwaway account that trusts that TradeFortress account we can send these useless RippleBTC to that are otherwise inflating our genuine Ripple balances?
This thread is full of addressed who trust TradeFortress, you can send the BTC to any of them, but why would they give you anything in return? You can also create a trade offer, just change the "issuer" to TradeFortress for BTC and you can offer to sell them for any currency you want.