Any contact added in SR web will also be updated in the app?

Any contact added in SR web will also be updated in the app?

Yes, all the contacts from the SR web account are auto-synced in the mobile app as well. If you add any new contact on mobile app or web app it will be available in both mobile and web.

To know how you can add a contact in the mobile then you refer to this article: 
How to add a contact?