What should be done with the iPad that the sister found on the bus and no one asked about? Is it considered theft for relatives to benefit from water stolen by Jews to irrigate their crops, and what is the ruling on accepting their gifts from these crops and buying their agricultural products?

The device your sister found on the bus is considered a lost item (Luqatah), and it must be announced for a year, after which she can take possession of it, provided its description is known. Your sister made a mistake by bringing it to Palestine, because the announcement should be made in the place where it was found and its vicinity. What is obligatory upon her now is to announce it in that place and its vicinity, or to hand it over to the office responsible for lost and found items.