Thank you for taking your time to answer my questions
Kosher – There are very limited options for mehadrin eating in Ramat Aviv / Tel Aviv, both in restaurants and in supermarkets. Can I rely on the hashgacha of Rabbanut Tel Aviv? I spoke to several of the religious students in upper years and most of them use mehadrin meat, but eventually switched to rabbanut dairy, but I don’t know who/if they asked.
Yom Tov – Since I am now living in Israel for at least 3 or 4 years, do I keep 1 or 2 day yomim tovim?
A far as kosher standards I don’t know enough of your background and where you are holding to give you a psak. If you want to know whether it is assur to eat rabbanut I hold it is not treif and therefore not assur. If you want to know whether it is a standard you should feel comfortable with I would need to know more about you.
As for your yom tov status you should keep one day for now unless your plans change.