Hi I do use icloud email on my phone. It works fine as far as I can tell. I use outlook so can't comment on the stock email app but can't see why it wouldn't.
You need to create a app specific password on icloud via a Web browser which is a pain and enter you email and the random password that generates to get your account on the phone. I was trying my email and icloud password, that doesn't work anymore it needs to be an app specific generated password from icloud. That's the only thing you need to do but that is strait forward. Just apple being awkward for daring to use anyone other then them.