Dow Jones futures will open Sunday evening, along with S&P 500 futures and Nasdaq futures. Warren Buffett said Saturday that trade shouldn’t be a “weapon” as Berkshire Hathaway (BRKB) reported a bigger-than-expected first-quarter earnings. Palantir Technologies (PLTR) reports Monday in another busy week for earnings. The Federal Reserve meets Tuesday-Wednesday, with investors looking for insight into possible rate cuts in…