In reference to Board Question #26926, the NIV translation, which I highly recommend for understanding the Old Testament, gives the insight that the first verse refers to David leading the army campaigns. It makes a lot of sense here. This was the primary reason Israel wanted a king (1 Sam 8:19-20), the reason David was so popular (1 Sam 18:5, 16; Battles in 2 Sam 5, 8 & 10), part of Saul's downfall (1 Sam 18:8-9, 2 Sam 5:2), and interestingly, the primary reason for David's downfall (2 Sam 11:1) because he was led into temptation when he should have been leading the army. This interpretation applies well to the second verse as well (about Solomon) and could be extended to general duties. I personally think the verse in Acts can be taken quite literally, that he went out and preached and came back.
-Shteven the Over Time scholar.