Picture quality on ANY satellite, or any TV system depends on a number of things, like SD or HD, cables, quality of the TV.
Some channels are transmited at a "high bite rate", meaning more data to majke a good picture.
Other channels are transmited at a "lowbite rate", meaning there is less data and a drop in picture quality. YOu just have to look at how bad the quality on True MOvies is - as they transmitt at a low rate, as their parent company are cramming over a dozen channels on to one frequency.
F1 is on BBC, red button "streams", Sky Sports F1 (with either a SKy sports subscription or a HD subscription) and on Antenna 3 on Spanish TDT.
Dishes shoudl not need "constant realigning", unless thay have been poorly installed in the first instance, or the dish is installed in an exposed area, and high winds move or bend the dish. Rain will affect channels. As some channels are on "stronger" frequencies than others, these channels will alst longer in rain. Bigger dishes help keep signals in, but it still does not gaurentee 100% reception 24/7 - even Sky do not gaurenetee that in the UK!.