Hi there,
It is recomended that you use a semi-synthetic or fully synthetic oil in your Yamaha. Yamaha has thier own branded oil, but there are many other types of oil out there. There are many people on these forums, and we all have our opinions on oil... just don't use the standard old marine lubricant, or the cheapest stuff you can find. It's not the best for your engine.
I believe most manufacturers recomend using 92-94 octane or greater. In the United States (not sure where you're from) we use premium fuel which is usually 93 octane.
Hope this helps!
~Josh