Is it possible for me to just download everyone’s contributed parts at once or do I have to search for stuff on the forum and download and install each part individually? I’d like all the parts. Every last part!
You would need to download the individual parts and load them one at a time. Once done you can make a parts bin for them all so they can be loaded all at once. That would be a useful thing to do (and post on somewhere like github for others to use) but hasn’t been done as far as I know. Adafruit and Sparkfun (and possibly more companies I don’t know of) have repositories of their Fritzing parts in bins available on github.