You would be happier with an iMac that has the Radeon Pro 580X with 8GB of GDDR5 memory for FCP. Get it with 8GB of RAM and then purchase 32GB of RAM from either Crucial.com or Macsales.com and buy the largest SSD you can afford. Never buy RAM from Apple, way over priced! As iMacs are sensitive to using quality RAM I strongly recommend those 2 vendors as they sell very high quality products, have reasonable prices, offer lifetime warranties, and have great service.You can always buy external storage for storing large libraries such as your music, photos and movies.
As for your Windows needs, yes Boot Camp will work fine, however you may also want to look into Parallels which allows your to run Mac OS and Windows simultaneously. Unless you are doing some serious gaming or other graphics intensive Windows app using Parallels works great and is extremely convenient.
One last thing, buy AppleCare, it will extend the warranty to 3 full years and is worth every nickle in the event you suffer a hardware failure outside the normal 1 year.