Whenever you pay one year in advance things can get a bit more complicated than they already are when it comes to billing. Basically when they shut you off early on an annual account and you was charged for 11 months instead of 12, they go back and charge you the monthly fee for each month over the past year instead of the pro-rated annual fee. This means that if you paid for 12 months in advance and you call in when 11 months is up it would cost you the same as it would be if it were prepaid for 12 months. If you are not getting much of a discount anyways like in this case where you only save $3 a month, then it would not be much of a concern.
Make sure when you prepay the one year of AT150 that if you downgrade at some point during that year then you will receive the credits for the remainder of the months you did not receive the service but will be charged based on the monthly service instead of the annual service.
If you upgrade during the annual prepaid period then you would have two choices, to add the additional services to pay monthly until the next annual bill comes on the other programming that you paid annual for or to pay annually on those services but it would not go along with the same time you paid annual for the other programming.
Basically you would end up paying annual for Top 150 at the end of December and paying annual for the other packages that you selected at that time, so if it was February when you added services, you would have to pay the annual amount everytime February came around or pay the monthly fee until December come around so you can put it all together for an annual all in the same bill.
Of course, you could prepay into your account before the annual bill would come around and it would cover that amount for the annual bill. If you added additional services after that and wanted to do it on a monthly basis until the next annual comes then you could prepay the amount it would be for all those months until the annual bill comes out again so you would not have to send money in each month. This is why credit card autopay is so much more convenient, it could just be prepaid and if there are errors on the bill then the credit card company could help handle it for you.