I was thinking a higher loft (11.5 or greater, due to less sidespin) AND a DRAW bias over offset, personally.
I can hit straighter if I hit the driver daily at the range but I don't have the luxury of doing that now that the weather is changing and it is dark after I leave work. I am playing in the South during Thanksgiving and I want to hit something more consistently and more confidently. I just ordered a higher lofted driver than what I have now (12 degree versus 10.5) with a draw bias since I was hitting demo clubs more consistently straighter and as far with that configuration than I was with my current driver and other configurations (neutral 10.5, draw 10.5, etc).
Loft plays a more important role in straighter ball flight than the other variables that you mentioned. Spin is going to affect the shot the most. You have the right idea in seeking a higher loft, however, I think that you should get fitted on a launch monitor to maximize all aspects of your new driver.
I think probably all of those can help correct a slice, but I would say that increasing loft is the best single way to minimize it. The higher loft will give more vertical backspin and minimize the side spin that makes the ball slice. I would agree completely with "stevenmgrr"...go get professionally fitted for a driver. That will save you a lot of money and a heap of frustration in the long run. I use a 400cc, 13 degree driver with some offset a lot, and I find it really helps to cure my natural tendancy to slice.
I would recommend a higher loft driver, like the one you ordered. I to have a 12* and a 11.5* driver, and I hit them both better on average than a 10.5* model. Of the things you mentioned, I'd recommend you forget about "offset" drivers. Think about it, all the offset does is cause you to contact the ball a little later in your swing, due to the head being farther away from the ball in relation to the shaft. Truth is, you can do the exact same thing, just by teeing up the ball a 1/2 inch farther forward in your stance. And that's free, you don't have to buy a new driver or a new tee, just move the ball forward a little. And you can vary it as much as you "NEED", to get a perfect fit for your swing. Think of an "offset driver" as a "Bandaid fix". It's not a cure, it's a fix, and what you should be looking for is a cure. Learn to hit the ball straight, with lessons if need be, and you will be much better off.
go for the lesson, and i think the driver you have should be pretty easy to get in the air so maybe its the shape of the thing thats messing with your head, a good swing path and youll be switching to 8.5 degree drivers