for most nudibranches well really do not know what they eat so alot of them die in captive care. but with lettuce nudi they eat hair algea I kept them for about a year or so I found once you run out of hair algea they die off. there one of the easy ones to keep b/c we have an idea of what the eat.
Yup. I have 2 of them. Hair algae, primarily bryopsis, is their main diet. They are actually pretty hardy, but will starve in the absence of hair algaes, or macros.
Yeah...I hear powerheads are bad news for them. Make sure your intakes are covered. I use maxijet powerheads, that have a nice screen over the intake.
I am not sure about the nori strips, but it may work. I don't think they pose any danger to anything other than the algae...