Freedom of speech is broader than that. Freedom of speech not only extends beyond congress (which the Supreme Court has repeatedly affirmed), it also goes beyond political speech. You have the right to espouse openly racist beliefs. You have the right to espouse religious beliefs, and beliefs on the best way to grow corn, and what the best auto maker is. These are not political opinions except to the extent that they are protected from suppression by politicians. (Alternatively you can argue that basically all speech is in some fashion political, in which case the "political" distinction is meaningless.)

This is actually illegal in many states. Workers have a legal right to discuss salaries.

>Freedom of speech pertains to legislation from congress preventing political speech.

Not correct. Free speech is about any freedom of expression, not just political speech. There is endless amounts of case law to back this up.