Short answers, pulled from the story.
Tacitus Histories covers the period from AD 69 following Nero's death to AD 70, which includes the rapid succession of Galba, Otho, Vitellius, and Vespasian. The surviving text ends in early AD 70 after covering the year 69 and the first part of 70.
Only the first four books and the first 26 chapters of the fifth book remain today. Together with the Annals, the original work amounted to 30 books according to Saint Jerome's explicit reference, but about half of them have survived to the present day.
Tacitus believed that after the Battle of Actium, unification of power was necessary to keep peace and fidelity of the armies. He argued that an emperor must be able to keep the imperium safe while saving the prestige and dignity of the Senate without being a tyrant like Domitian or a fool like Galba.
The text describes how Titus was placed in command of the war during AD 70. This section serves as an invaluable record of educated Romans' attitude towards the ancient Jews and occurs within the same timeframe covered by the surviving chapters.
The style of narration is rapid, reflecting the speed of the events described with no space to slow down or digress. Tacitus skillfully shows characters by alternating short and sharp notations with complete portraits using irregular constructs and frequent changes of subject.