Yamalube at 32:1 is a great choice.
There are lots of great oils out there, and everybody will have their favorite to tell you about.
My preference is a Castor based oil, Maxima 927 or Castrol R30, but there are lots more. Casrot oil or bean oil as it is reffered to, has been proven as the best oil you can use.
As long as the oil is designed for air cooled motor cycles, the choice is yours.
Never choose an oil designed for weedwhackers, chainsaws or outboards they are not good enough to stand up to the alternating temperatures and punshiment a cycle engine is dealt.
Ratios should be 32:1 or more oil unless stated on the bottle. Some makes of oil can be used at a lighter ratio, but I would never take the chance.
I run Casrtol R30, at a ratio of 25:1 for extra compression, and peace of mind that I am doing a good thing to ensure my motor will last a long time.
Pay attention to the jetting as changing oil ratio, also changes the AFR, so by adding more oil you will run a gas lean mix, which leads to overheating and damage.