Yes, your Non-OA will be valid for one year after application, so you have enough time to enter the country. The insurance must be for one year, beginning from the day of arrival, otherwise the will give you a shorter "permission of stay".
That not completely correct... you still can renew it up to three years. After more than one year you have to do the theoretical test also, after more than three years also the practical test... that means actually you start completely new.
No, you don't need a return ticket, but you might need a "leave the country ticket". That can be by plane, train, bus, boat. Mostly the airline will ask for that at check in, hardly the immigration. But if the IO has a bad day... then...