Yeah, the LTE thing is dumb and kind of annoying, though I guess in my case I should balance it against the fact that I haven't paid for data on the S for the past 4 years.
I'm not sure how the hotspot thing will work, or if it will. Yes, you can set the Model S up to connect via wifi, and it looks like the Model 3 does as well:
https://teslamotorsclub.com/tmc/thre...onnect.121916/
Will the car still pull map data/slacker audio through wifi if you don't pay for the LTE connection? I don't know, but I don't think Tesla does either since AFAIK they haven't implemented this yet.