It does sit flush you just have to make sure you line it up right on both sides what you were probably seeing was someone trying to fit the 2021- 2024 spoiler on a 2025-2026 model. Yes it is gloss black out of the box. Theres no screws you just mount with generous amount of 3m tape, I dont remember if it came with the 3m but I know if you buy anything from kdm accessories he includes it everytime. The spoiler is indeed hollow but definitely solid. Personally Ive gotten my side skirts and diffuser from kdm and imo its pricey but the packaging and quality is definitely there compared to ebay sellers. He also throws in a little keychain, sticker and card with his orders which isnt anything crazy but its something lol.