I have the blockbuster service. 3 movies at a time. I record them on DVD-RW and send them back the next day. I watch it when I want to then I record over the same DVD-RW's when the next 3 arrives in the mail. I use DVD shrink and DVDfab Decryptor. I'm paying for the right to watch it, the copies are destroyed afterwards.
As for netflix, a friend of mine uses it and said he got flagged for high usage. I don't know what he meant by it. I guess they started to wait a few days longer to send the rest of his que.
They send out the next movie on the list when the service receives the previous ones. Different plans depends on how many movies are sent at a time.
With Blockbuster, you get 2 free rental coupons a month.
and no, copying a DVD does not alter the originals.