hey guys can anyone help.

I wonder if anyuone can help with the following 2 shipping options I would like to offer on my site, and how to dothis in the admin section

1) I want to offer FREE postage for people using Google Checkout only
2) I have installed a shipping of £xx per item - is there a way to have so much for so many items

for example - 1 item £3.00, 2 items £4.00, 3 items £5.00
rather than 1 item £3.00, 2 items £6.00, 3 items £9.00

A combined postage rather than the£3 per item

Thanks in advance