I have the m80s myself and they are excellent! The m60s use mostly the same drivers and are supposed to be very good, too.
To answer your questions, no need for the die cast or bi-wire options. In fact other than aesthetics the only option I'd suggest is the spikes if your listening room has carpet.
As to whether your amp is powerful enough, what speakers do you have now? How sensitive are they? The m60s are listed as 93 db anechoic, 97 db in room. If what you currently have are about the same or less sensitive then the m60s should be able to play just as loud or louder. Only if your current speakers are more sensitive might there be an issue if you like it loud.
Then again, you might be more tempted to 'crank it' with your new speakers. Running an amp at or above clipping is notoriously hard on speakers so if you notice it happening by all means you should turn down the volume and consider upgrading your amp.
Enjoy your new speakers!
