A few questions regarding true tire size as compared to their advertised size

I have a 2003 Honda Rubicon, with the 25" dirt hooks. I am planning on buying a Can-Am Outlander Max 650, which has the 26" Carlisle ACT radials. I am considering putting the ACTs on the Rubicon and putting Kenda Bearclaw HTRs on the Outlander. Questions:

1) ACTs are said to run smaller than advertised. Is it closer to a 25" or 26"?
2) HTRs are said to run true to size, so 26" equals 26"??
3) Rubicon - Are the stock Dirt Hooks true to size? Would the 26" ACT be an inch taller, or would it not be too far off from the factory size? If it is considerably taller, will the Rubicon have trouble turning them? I live at 7,400 ft, and ride anywhere from 5,000 to 9,000 ft.
4) Outlander - If the factory ACTs are truly small, should I go with the 25" HTRs, or should I stay with 26" HTRs and reap the benefit of the taller tire? How will it affect the performance of the Outlander?

Thank you!