What languages did Chanakya and Chandragupta speak?

Chanakya was a resident of Taxila in Mahavansh Tika and as per Parishisth Parvan he was resident of Chanaka village in Golla District. Chanakya was a learned man of his time and he would have spoken Sanskrit, Pali, Magadhi (as he spent a major time of his life in Patliputra as it's minister and power behind the throne) and the language spoken in Taxila that time and probably he also knew kharoshti script. The similar languages were known to Chandragupta Maurya as well because since his young age he was studying under Chanakya and spent a lot of time with him.

If Chandragupta Maurya was indeed Sandrocottus, he might have had known a little bit of Greek and Persian as well if not fully fluent.

Who were the wives of Porus and Chandragupta?

Seleucid Princess (Wife of Sandrocottus)

The information on wives of Porus is not available but he had sons who died in war with Alexander so obviously Porus was not a very young man when he met Alexander and as a king, he likely had many wives but the information on his family is not available.

The wives of Chandragupta Maurya are mentioned in Parishisth Parvan and Mahavansh Tika.

Chandragupta and Durdhara

Chandragupta and Durdhara were King and Queen of the Mauryan Empire. She is said to be daughter of his eldest maternal uncle who had come to Patliputra with the King’s mother. He wedded the daughter of his eldest maternal uncle and raised her to dignity of Queen Consort and she was mother of Bindusara. The name of mother of Bindusara is Durdhara in Parishisth Parvan.

Both sources mentions that Chandragupta had many wives and Durdhara, the main Queen , had died while pregnant due to accidentally eating poisoned food of Chandragupta. Her baby was saved through timely Cesarion. Chanakya used to mix poison in his food to build his immunity but without informing the King.

Nand Nandini (Daughter of Nanda)

A daughter of Nanda was one of the wives of Chandragupta Maurya. The marriage happened after he had defeated the Nanda King. Parishisth Parvan tells a dramatic story that she had fallen in love with him at first sight and he rejected her but later accepted her due to Chanakya. Most likely the marriage was a strategic alliance where chandragupta gained legitimacy in the conquered Empire and she could continue her royal life as a queen. There is no information whether they had any children or not.

Seleucid Princess (in Indian royal dress after marriage to Sandrocottus)

Seleucus and Sandrocottus had a marital alliance after their war. Sandrocottus is identified with Chandragupta Maurya. Seleucus gave up Kabul, Kandhar, Herat and Makran (Baluchistan) and in return got 500 elephants and a marital alliance.

Historians opine that a marriage happened between Sandrocottus and Seleucus and Seleucus gave one of his daughters to Sandrocottus as his wife. The princess was likely quite young when she got married. It was very unusual for a Greek king to marry his daughter to a non Greek king , so, it's likely was deliberately not recorded in Seleucid Chronicled, specially when he was trying to portray himself as supreme King in Hellenistic world.

Was Nandini married to Chandragupta?

 

Chandragupta Maurya and Chanakya with help of Parvatak and after great efforts had successfully captured Patliputra.

After Dhan Nanda pleaded mercy to Chanakya, he allowed him to leave with his important things for his sustenance which his one chariot could hold.

Nanda took his two wives, a daughter and loading his chariot with treasures he left the city.

When the family met Chandragupta Maurya on the road, the daughter of Nanda sitting in the chariot fell instantly in love with Chandragupta at first sight (probably due to his handsome appearance). With her side glances, it looked like she was infatuated with him.

Nanda allowed her to choose her own husband as Swayamvar was considered befitting of a princess.

She left her father's chariot and ran towards Chandragupta’s chariot. When she put her foot on his chariot, nine spokes of a wheel broke.

Angry Chandragupta shouted “Who is this inauspicious woman trying to climb my chariot?” He forbade her to climb his chariot.

But Chanakya told him to stop her and not think the accident as a bad omen but an auspicious one. It meant his dynasty would run for nine generations.

So, after Chanakya told him this, he (half heartedly) accepted the Nanda Princess.

Source - Parishisth Parvan

The story seems a little dramatic and it might be possible that after the conquest of Magadha, Chanakya advised him to marry a daughter of Nanda. The daughter unable to change her fate and founding the new King good looking didn't have much problem in accepting the new reality but Chandragupta had his doubts. But ultimately Chanakya convinced him to marry her for the good of his dynasty.

The Princess is mentioned as ‘Nand Nandini and ‘Nand Duhita’ and this might be the reason for this Nandini name but it wasn't a name, both terms means daughter of Nanda. The name of daughter of Nanda is not mentioned by Hemachandra, author of Parishisth Parvan.

The aftermath of their marriage is not mentioned in the source, there is no mention of his conflict with anyone of his queens. So, it might had been a tolerable marriage for the couple if not a very loving one.