Updates - that can happen with some firewalls. I used to get that and had to turn off my firewall. The problem has gone for me. One way is to download the update only and then install but it is some time since I did that.
Facetime is Apple only eg iPhone to iPad, iPad to iPad or to a Mac. It is actually quite good and I have found it better than Skype but limited to who you can call.
Skype is a available as an app. It works quite well and you can switch between front and back camera. This is very handy if you want to show someone a room or scenery.
OnePlus 5 review