This is actually fascinating. T-Mobile doesn’t need a fiber or even cable buildout to a remote location, just power and the local clearances for a tower, they plop a Starlink antenna on the top and bam. Congestion will be a challenge but it will be way better than the current status quo.
Not if they use the regular frequencies. It'll require a pretty sensitive receiver though, no point in steering the beam if you don't know where the recipient is.
That isn't what this is, but they did mention maybe partnering for backhaul in the future (likely with similar tech and frequencies to the home internet, not the frequencies in this announcement).