Hitachi hdr253, Freeview.?

I have just purchased an Hatachi Freeview HDR253 Digital Recorder, and i would like to know can you edit the recordings on the HD, for example if i record something off a commercial station, can i later edit the advertisment out of this recording (not using to pause on as its recording but after it allready been recorded) so then it can be copied to a dvd using a dvd recorder without the adverts. Also why is there a ariel out socket on the back of this unit if Freeview wont travell down it and og is being switched off, lastly the aux/vcr scart socket on the back of this unit is it signal in or out. thank you