It would be best on a big c/ku motorized dish but you can use it on a 90cm or 1.2 meter dish I recommend a motorized setup, look here for the free dvb feeds http://www.lyngsat.com/
As for hi def, I think PBS makes up the bulk of what's available.
Hunting "feeds", may get you some special events, field news reporting, sporting events...
Unless you are interested in C-band satellites (the 8..10 foot dishes), that's about it.