re the bootloader:
I have and use ICSP programmers for the tinies I develop but, especially when breadboarding , I include a 6 pin straight header for hooking up a USB-ttl serial cable. This is great for debugging.
Presumably, to be arduino-like, a boot loader could be automatically grafted on to the sketch(like init) and get a shot at the serial before the application started.
I think that would be convenient. I also imagine it would be trouble-prone but I guess that would depend on the implementation.