Regarding sending titles to 'preferred' or new customers.
Whether it's 'right' or 'wrong' can be debated, but most companies do prioritize their customers. Sometimes with reason [contract status, big spenders, etc], sometimes with questionable reason [bonus to new customers, etc].
But I think it depends on a couple of things;
first, how new a customer you are. They probably put new customers at the top of the list, because once a new customer stays for X months, they're 'stickier' and less likely to drop their membership.
Secondly, how many disks you rent. They might throttle your renting if you're renting a lot more than the 'average'. Much like if you go to an All You Can Eat restaurant, they may do the same [ever notice how long it takes the server to bring you that second or third plate of ribs or shrimp, or how long to put out a new pizza on the buffet sometimes?]
And third, what you are renting. If you're constantly renting brand new, in-demand titles, obviously they bought more copies, but their demand still might outstrip their inventory. So they probably have some formula to measure Newness; Disks Rented; Popularity of Disk; Length of Rental Queue, to see which customers have 'priority'. So if you're a brand new customer, you have 3 things in your queue, you haven't gotten any disks yet, and the 3 things are brand new bigname releases, you'll probably get them before, say, me [old customer, big queue with non-popular stuff, medium rental activity.] My queue currently has 151 items, probably 75% of them are anime, foreign, tv on dvd, or 'cult', and everything says Now and my turnaround time has been about 1.5 days. [Put something in the mailbox yesterday midday before the mailman came, queue currently says a new disk is shipping today.] I do live only about 100 miles from a distro center, so that does help, but I was getting decent response time even when it was going to Maryland from NC.
I am glad Netflix is reacting to competition, though from what I've heard, the competition doesn't offer much competition at all in terms of quality, selection, or speed. But many people think 'cheaper is better', so they may join Walmart's service instead of Netflix to save a couple bucks, even though NF does offer a lot more than WM.