A few questions about android 7 on a new phone Why does my mobile provider only show in the topbar on the lock screen? How can I get it to show on the topbar when unlocked?

Also in the drop down menu with the icons for some often used settings I see "no sim card", what is this for? I thought maybe as I can't see the provider in the topbar that there was a problem with the sim card, but I without wifi I was able to call someone.

When I look at the sim "settings->sim cards" there is a telephone number on my sim card, but it is not mine (the card was new to replace my old one). Is it ok to update this number?
Apparently, on dual SIM phones, this is normal. The provider name will only appear on the lock screen. 

Also, in the quick settings menu, it is normal to see the 'no Sim' setting. It's there in case you do insert a second Sim, you'll be able to change different settings.

There is no problem with changing the phone number in Sim settings, to your current number.