Jamieson, Fausset and Brown on Acts 24:27

27. after two years--What a trial to this burning missionary of Christ, to suffer such a tedious period of inaction! How mysterious it would seem! But this repose would be medicine to his spirit; he would not, and could not, be entirely inactive, so long as he was able by pen and message to communicate with the churches; and he would doubtless learn the salutary truth that even he was not essential to his Master's cause. That Luke wrote his Gospel during this period, under the apostle's superintendence, is the not unlikely conjecture of able critics.

Porcius Festus--Little is known of him. He died a few years after this [Josephus, Antiquities, 20.8.9-9.1].

came into Felix' room--He was recalled, on accusations against him by the Jews of Cæsarea, and only acquitted through the intercession of his brother at court [Josephus, Antiquities, 20.8,10].

Felix, willing to show the Jews a pleasure--"to earn the thanks of the Jews," which he did not.

left Paul bound--(Ac 26:29)--which does not seem to have been till then.