I would choose 1 or 4, depending on which you would use more, a portrait lens or a landscape lens + extension tube. I think adding a new camera system, while the most fun option, adds complexity to your life and surely comes with hidden costs, like new film and perhaps new developing and printing equipment. I guess what I'm saying is, I wouldn't add an entirely new system unless I was sure I had a use for it, not just a yearning to try something different. I say this from experience.
That said, I think there is nothing that will help your photography more than proper light metering. So, if you have no external meter at all, then I'd not buy any new camera equipment until I bought both an incident and a spot meter (sometimes available in the same meter).