The phrase "first and last" represents the whole time of Solomon's reign. Alternate translation: "from the beginning to the end of his reign" (See: [[rc://en/ta/man/translate/figs-merism]])
The author uses the question to remind the readers that other people had written about Solomon. It can be expressed in active form Alternate translation: "they are written ... (which also had information about Jeroboam son of Nebat.)" or "people have written about them ... (which also had information about Jeroboam son of Nebat)." (See: [[rc://en/ta/man/translate/figs-rquestion]])