John,
As to your question #1:
I can't say which is the most prefered way to mount a scope on the Tikkas, but I have used the rings AND bases from the optilock system. It cost a bundle, but they are rock solid. I did this at the advice of many gunsmiths. Then again, you have a .22-250 so recoil is not a factor. I have a .25-06 - which still isn't that much of a factor, but it's still money well spent.
As to your question #2:
I'm not quite sure what you mean, but actual scope mounts will have little, if not nothing, to do with eye relief. Now, some people may want the scope mounted lower or higher, but that has nothing to do with eye relief. Again, I may have misunderstood your question, so please elaborate if I am wrong.
As to your question #3:
see answer to #1.
Hope this helps.
Zachary