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I have no information about availability of SQL 2025, but based on experience, I would guess that it will be available no later than end of January 2026. I would not hold my breath that it will appear before Christmas.
PBIRS is not included in the package as such, but as I understand it, it is included in the license. But that assumes that you install PBIRS in the same machine as the Database Engine. (Just like it was the case with SSRS.)
Software Assurance will certainly still be available. I have not heard anything on the contrary, and it would be a huge disappointment if SA was discontinued.
Note that this is a technical forum, and your questions stray beyond the scope of the forum. You may get better answers if you contact your local Microsoft representative.