No, that isn't true. The lack of a Unified Field Theory is just one example how the current language breaks down. Different scales of nature have different rules, again I am just pointing out the incompleteness of our ability to speak a "Universal language," let alone there really being one. I think it is like a limit that approaches infinity, it never actually becomes infinite (
See: Cantor).
Pi as a value (3.14...) exisits in our number system. It depends on what base the counting system employs that will give that value. Like I orignially stated, the concept as a "ratio between the diameter and circumference of a circle," should by all rights be Universal but that assumes we could reconize the alien descriptions of both a circle and how this ratio was represented. Just because binary underlines the majority of our technologies does not mean all other extra-terrestrial technologies operate under the same paradigm. Would a binary framework work with quantum computing? No.
If by primer, you mean cypher (I don't think you mean finding "How to Speak Alien 101") then its an assumption that we would recognize that "code" let alone be able to decode it with whatever types of mathematics that were employed. It would take a sort of reverse-engineering an alien "Enigma Machine," highly speculative.
I love Carl Sagan. It seems like you are coming from his position in this matter and I agree he was a brilliant guy. These statements about mathematics are too general to be always true, hence there is no proof for what you are saying due to the existence of contradictions. Thinking that the math equations we have, developed through Algebra and other maths, are Universal is an Earth-centric point-of-view. It is an interesting thought-experiment to think about what this all means and how could other maths exist; discover one and you could be the next Liebniz, Newton was a prick and we don't need anymore people that consider themselves God's gift to our civilization.
The point I'm trying to make is just that mathematics is not singular for a reason. To assume extra-terrestrial maths conform to our maths is something that could only be proven retroactively; that is to say, only if it happens will we ever know.
I encourage you to look deeper into the diversity of mathematics, if you are interested, it can be just as profound as speculating about aliens.