My dear Heraklia, I cannot keep you suffering... and will try to answer your questions.

All the authors quoted are clear in stating that Calpurnia's marriage to Caesar took place during his first consulship in 59 BCE (reading Dio you might be led to think the following year, 58). I would argue for an early date in 59. So they were indeed married 15 years.

When Caesar made provision in his will for an eventual son he could not be thinking of Caesarion. Even if he believed him to be his son, he was the son of a foreign woman and as such by Roman law could not inherit. Nor did he need to, being heir to the twin crowns of such a rich country as Egypt :-)

He certainly could be thinking of a son by Calpurnia, who was still only about 30 at the time when Caesar drew his will, in September of 45 BCE, on his return from Spain. The will in which he named Pompey heir must have been drawn in 59 BCE after Pompey's marriage to Julia, and was revoked at the beginning of the civil war (for the dates, see Suetonius, Caesar, LXXXIII). I think in changing wills he switched from Pompey to Octavius, but probably always had a clause about a possible biological and legitimate son.

As for Calpurnia's political position during the triumvirate years - after she entrusted Caesar's papers and money to Antony, she disappears from the scene and the only reference to her is the Ikadion epitaph. We know her father tried to made peace between Antony and the Senate, and took Antony's wife Fulvia and her children as houseguests for their protection (Appian). He isn't heard of again either after the setting up of the triumvirate, but his son was a patron of Horace and became consul in 15 BCE, so we may assume that the family was in good relations with Augustus.

I'd say that Calpurnia, a cultivated Epicurean, kept her usual low profile and lived quietly among her friends and family.