It's not difficult at all. Of course actual vampires or people with senses to recognize them might not be as easily fooled even with Ultimate talent.

Most young vampires/newly turned need to feed at least once a week, but with "age" they start needing less - going as far as not needing blood for two months at a time. Of course some eat more often just to make sure they won't become hungry predators.

Dealer's choice! You can either have them be unaffected or play with a mixture of the curses.