This would be my first attempt at purchasing and using the pi for any use-case. I am attempting to build a full bitcoin node using raspberry pi (which is I/O heavy). I plan to purchase the a.) motherboard (Pi 3), b.) case with fan, power adapter, and c.) USB HDD ~250 or 500GB. Two questions
Does the rPi need a microSD to boot, or can a USB HD work?
Will microSD cards available online meant for phone cameras work as intended on the system?
There seem to be microSD of 256GB available for ~20$. I was curious if i can go with just a microSD and avoid the USB HDD.
I want to optimize for physical space over performance (but obviously performance should not degrade to a point where it doesn't serve its purpose).