Metal sheds are very cold and prone to condensation, so be sure to line it. Also be careful with sealing it along the bottom - if you are standing it on a concrete base, there will be inevitable gaps where metal and concrete meet. The rats will still be there too, so will get in through the pop hole even during the day - try to get rid of them before the new shed goes up. We have noticed with our brand new metal garden shed that where the roof panels are bolted, the rain comes in at a couple of points - we can stand a bucket under them, but not in a hen house. You will need free standing nest boxes.
To hide the now bad view, plant tall trees and dense shrubs like holly as far away from your viewpoint as you can, so you are not shaded but the new boxes will be hidden in a few years.