Initially the hotspot will work in 4G areas without requiring the $29.99 add-on due to a glitch in the way authentication will work on the 4G network. This will be fixed shortly after release. 3G hotspot functionality will require the $29.99 add-on immediately at launch.
levi calls will only come through while using hotspot only if your using 4g. 3g calls will goto voicemail. i agree with you calls r more important. if i'm on the net now with my phone calls still come through. hope that is something they will fix for us 3g users.