ITV1 HD is available on Sky, Virgin Media, Freesat and also on the new Freeview HD service (where available). The EPG number for Sky is 178, for Freesat 119, for Virgin Media 113 and for Freeview 51
Yes, there are few of the bigger regional ITV HD versions now, some are encrypt (on Astra 2B) and some are FTA (on Astra 2D) mainly for creating advertising super-regions. STV HD is also testing.