to use as a wifi hotspot for up to an hour during the day on occasion so I can listen to streaming music while driving around.
I'm not sure what you mean here
the watch can't be used as a hotspot (it can connect to cellular, but no other devices can share that connection)
and if it did, you could probably take several hours off of the battery life estimates listed here.
you can pair bluetooth device to it (like headphones)
but... unless you have Apple Music you can't listen to music
as of now, Apple Music is the only service that lets you sync music to the watch, or stream live.
The Spotify app is just a remote for their app on the phone.
it is starting to change, I think tune-in will let you stream radio stations, and several podcasts apps will let you sync
You need to research whatever services you use, start with the assumption that it's not going to let you listen directly from the watch.
the watch won't replace your phone.
depending on what you're trying to do, you'll probably want to grab your phone.
Going out for a run, or a quick errand, you'll probably be OK without your phone, But most of the time, you're going to want your phone "close" (not necessarily within arms reach, but grab-able in a few minutes)
for anything more than a quick reply, you're going to want a "real" keyboard and a screen that shows more than 15 words at a time.
also the watch turns radios on and off as needed. in order of power those radios consume.
If your phone is close and connected via bluetooth, wifi and cell are powered off.
if you loose bluetooth, it will power up wifi and try to find a network.
if it can't find that, it'll turn on cellular.
Cellular uses a lot more battery than the other 2, so if you're relying solely on that, take time off the estimates listed above.
