As far as I am concerned, you can use without problems the latest WAS 8.5.5.X release.
I suppose, but never had the chances to test it, that WAS 9.X will also work, BUT you must check with your IBM sales representative, if you are allowed to use WAS 9.x, since CMOD V9.5 is a bundle that contains WAS 8.5.X licenses, which might not include the license to use WAS 9.x. So you need to check that point with IBM in your specific case.
Concerning Java, you can use Java 8 with WAS 8.5.5.X, so you should be at the latest on that side.
Concerning ODWEK, since CMOD and ODWEK are since V9.5 together... as long as you install the latest CMOD, you have at the same time the latest ODWEK. (time of writing V188.8.131.52)
If you use the Content Navigator (ICN) then you will have the latest CMIS interface included in ICN installation. That will also help to keep you up-to-date.
About Version Next (v10, V9.6, V10.1, whatever the exact version will be), I have heard/read that it might come in a few month... but again, this is not sure...