Yes, in order for your company to have opted OUT of the end-of-service gratuity it would have to be in your contract. Otherwise, it's there. Secondly, I don't know of any rules that say companies must give an NOC in such-and-such circumstances. It seems to be totally up to their discretion. Finally, if you have been on a family visa you don't need an NOC to re-enter after your RP is canceled/expired. Only the worker needs an NOC and he/she ALWAYS needs an NOC within the two year time frame.
Mandi