Hey, congrats on tackling such a big project! Windows can definitely be overwhelming with all the choices out there, but you’re asking the right questions. For energy efficiency, always check ratings like Energy Star certification and consider double or triple-pane glass for better insulation. As for installation, whether you go with or without a flange often depends on whether it’s a new build or a retrofit situation. Flanged windows are usually easier for new construction, while non-flanged ones are perfect for fitting into existing frames. If you need a complete, step-by-step breakdown, Open covers everything you need to know. Good luck with your reno!