Projecting onto a wall can work, but you'll get better results with a dedicated projector screen. The screen will provide a smoother, more reflective surface, which enhances the image quality. For your room size, a 100-inch screen should be perfect. As for resolution, 1080p should be plenty for bedroom viewing, but if you want future-proofing, a 4K projector might be worth the investment. Look for something from these brands: BENQ, ViewSonic, Epson, or Optoma.