The brightness of an image on your screen is higher than an image printed on paper due to your LCD screen being backlit. The "book" module is probably using "soft proofing" to show you what the image will look like on paper. It is very common for printed images to need a little extra brightness when printed.
It shouldn't be. This is usually a sign of a bad monitor profile (recalibrate your display and make sure to calibrate to a v2 icc profile) or it is a sign of over sharpening a high ISO image. The preview of sharpening and noise reduction is incorrect in Develop if you are not at 1:1 or higher zoom ratio and if you touch the sharpening sliders when you are zoomed to Fit or Fill, you can get off track and over sharpen by a large amount. This sometimes gives images a lighter appearance in Develop than in the other modules.