Motion sickness is very unpleasant, but keep at it just as you are now. Just build up your time ‘under the hood’ a little bit at a time. You should find that you will soon be able to endure longer sessions. Definitely end a session if you start to feel the onset of feeling queezy.
As for getting the best performance out of your O+, @fearlessfrog helped me out with this just the other day…
On top of what Fearless said, you should enable reprojection for WMR.
Here is a link to a post on the ED forums that shows how to do that…
I hope that helps, and welcome to Mudspike!