I'm not 100% sure, but I think the 5 code per 24 hrs limit applies to these as well, so enter as many of them as soon as possible if you're behind.
Fortunately, no. From the "enter code" screen, emphasis mine:
"Points will only be awarded for a maximum of 1 valid code per physical movie format and 5 valid physical movie codes in a 24 hour period. Bonus points codes are not subject to these limits. Visit FAQs for further details."
The Bluray/3D and the separate DVD have been available since the reopeningI think it was on Blu-ray.
For those that missed it as a Hot Reward, it appears the MULAN book will be opened again -- easily worth 1200 points if this kind of thing interests you at all
Nice movies, nice price, note the DVD packaging if that bothers you