Page 1 of Sony RDR-GX300 DVD Recorder - recording from Sky tv

Afternoon folks,

I am a complete techno novice but hope you can help me with the following:-

I have a Sony RDR-GX300 recorder as well as Sky tv (which is received through a dish.)
My question is - can I record a programme off Sky whilst watching a different channel and, if so, how do I do this? I`ve looked through the manual many a time but am still having difficulties working out if this can be done. Currently I am watching a programme whilst simultaneously recording it!

Also, which DVDs would you recommend if I wish to record over them? (I think the answer is the +RW format but wanted to confirm if this is correct.)

Many thanks in advance to anyone who can help!

Grant