AppleTV does support PSVue, and sling as well. It can also run DTVN if you wish. (in fact, ATT gives you one if you pre-pay for 3 months of service). Also, SlingTV actually has pretty decent quality, it's just the guide I think is lacking. Even PlutoTV does it right, and that's a free application. But the quality is fine.

You can login to the FS1 and 2 applications even though you have canceled service, because the billing cycle has not reset yet. You will have access for the remainder of the month, since you basically pre-paid for it. However, once the billing cycle goes through again, it will likely be revoked. Since you seem to like FS1 and FS2, if you subscribe to the orange package by SlingTV, those channels are included in your package. (as is Epix until 3/15). If you want ESPN as well, you'll need to subscribe to Blue+Orange. That will give you ESPN lineups, as well as FSN channels.

Regarding signing into Uverse, try a wired connection, or reset your box. Just so you're aware, using account credentials that aren't yours is technically illegal, and is piracy.

I also don't see any mention of an antenna in your setup. Go to TV Fool and run a report. Enter in your address, and it will tell you which providers are in your area, how to orient your antenna, and what type of antenna you will likely need.

Regarding your internet, that really depends. Comcast, Verizon, TWC, Earthlink, ATT, are all options. If all else fails, you could tether through your cell phone, or sign up for a WISP in your area. Go here to find a provider in your area:

http://www.broadbandmap.gov/internet-service-providers

https://www.cablemover.com/