1. Can I use the Uno as an ISP
or do I need to buy an ISP?
2. I've located the hex file for my sketch. Is it sufficient to load the hex file onto the ATTiny using an ISP (Uno or otherwise)
or do I need to load the Arduino bootloader as well?
Maybe writing your software in C with AVR-GCC and that won't be a problem. :\
I'm guessing I can load that onto the bare ATTiny using an ISP.