the patio is the back and there are no tress in the LOS of the dish just houses
It won't work, the houses will block the signal
I don't think a covered patio situation would work anyway unless the roof is made of fiberglass and you kept the wood studs to a minimum.
The easiest test before your purchase would have been to see if a 18" dish could receive signals from your covered patio -- to verify enough microwave transparency to work.
As for #2, if you have a cable appetite, FTA doesn't have enough unencrypted cable services to satisfy an appetite. You could partially satisfy it though raw feeds (live events like awards shows and concerts that would air on a cable channel) and some sports backhauls but you would be missing the studio shows and taped shows like documentaries or reality shows.
If you were just wanting something to watch to kill the time, there are more than enough FTA channels to do that.