Use a bootloader-programming tool like "optiloader" or "Nick's Board programmer" - much easier.(The "unused bits" errors is a backward incompatability in avrdude...)
Because you can't write to the buffer that you're currently executing code from?
in Optiboot, why does flash write need to go from serial to a ram buffer, then from the ram buffer to the boot page buffer?Why can't it go directly from serial to the boot page buffer and save the bytes used by the intermediate buffering code?
I've currently got Optiboot down to 0x01D4 (468) bytes
Hmm. Good question. Have you tried it? Would it save space? The RAM consumption is irrelevant...
I just upload either one to my Uno I am using as the programmer and then put the blank chip in the other Uno and follow Nicks directions?