ExFAT does make sense, since it’s the only filesystem which supports read and write on all major OS. Sadly it’s also pretty basic, and thus not the first choice on any OS - except for USB sticks.
I generally recommend formatting any new storage media before using it. Just to make sure it’s properly formatted to work with my machine, and the manufacturer didn’t mess up their implementation for some reason.
Most people using these sites prefer the lossless codec flac anyway, which can be transcoded to anything.
MP3 320kbps and MP3 V0 is transparent to most (all?) people, so there’s not much of a reason to go with a newer codec, except for space savings.
There’s not even much of a reason to go with 320kbps, as V0 achieves the same quality with smaller files. That’s why almost nobody actually downloads MP3 320.
I personally think MP3 is there for historical reasons, as I don’t see a reason for using lossy codecs for archiving purposes. Just download flac and transcode it once or on demand on a media server for streaming.