In my opinion, because I have Red Oak floors throughout from 1940, they are probably not quartersawn, meaning you see a lot more of the woods grain, which I think gives the wood a uniqueness that other woods dont have. Because of the wild grain, I think there would be too much contrast between the Oak, and say a Maple, or Cherry whose grains are a bit tighter. Why not keep using Red Oak, which also is a bit more cost-effective?

Well that's a pretty bed! Wood and green are colors from nature and I think any green will go with it beautifully. I think your bigger focus should be which green would work best with the lighting in your room. So, maybe you can post a picture of the room to show what kind of lighting it gets. Do you want a more vibrant or sagey or grayed green?

Oak white combo is not dated. This pic on This Old House site last week: Other pics: Paint your cabinets only if you want to. Do not get on the trend merry go round. Unless your budget is huge, you wont be able to keep up with the changing trends.

I would just change the sheen unless you want more contrast. I would not use White Opulence in this situation because they are both too close but too different. It would be just "off" in that head scratching way. Now I do know White Opulence very well,as I've used it for all my trim and all the kitchen cabs in this house.