--One has to purchase Arba Minim that were grown in accordance with the Halachot of Shmita.
--For all intents and purposes, the Etrogim that will be sold this year will be Otzar Bet Din or from outside of Israel
--It is virtuous to purchase Arba Minim that grew in Israel
--It is virtuous to use an etrog that has kedushat shviit.
--For Lulav, Hadasim and Aravot there is no Kedushat Shviit.
--An Etrog that grew in Israel during Shmita without heter mechira, and was picked during Shmita has Kedushat Shviit and you should treat it according to the laws of Kedushat Shviit.
--An Etrog that grew during Shmita and was picked after Shmita, should be treated as Kedushat Shviit, and one must take Truma and Maaser from it without a Bracha
--It is forbidden to take an Etrog that has kedushat shviit outside of Israel.