Definitely go with the gas. Yes, positioning is not fun, and your vision will not be so great for a while due to the gas. However, with the gas you won't have to undergo another surgery (if successful) and no bits of gas will be left in your eye since it gets completely absorbed by the body. Most doctors opt for the gas first and save the oil for more complex cases.
Go for the gas. Also, you really need to stay face down for at least two weeks.
Unusual to take out the cataract at the same time. They usually let you know before the surgery if the cataract is significant and they need to take it out.
Dr. O.