if you are going for freeshat for the HD channles you will only get bbc hd or ITV HD if you can already receive a bbc (not bbc news or pariliament) or ITV channels. c4 HD is only on a sky box at the moment.
many more channels are available on a sky box without a sky card than on the freesat EPG! and with your sky card you can get those ITVS and c4 on the stronger signal (12402 and 12480)...which you cannot get on a freesat box.
you can get all the recording and playback functions with a sky+ box. you need any sky subscription for these to be activated. even witrh a skyhd+ box (and no HD subscription you will get BBCHD ITVHD and C4 for free. all other skyhd channles you will need to pay an extra £10permonth.
for either freeshat+ or sky+ you will need a twin output LNB as minimum and two cables from the LNB to the receiver.