You can easily use a free Wifi network Zvartnots Public which is available on the whole territory of Zvartnots International Airport.
There are plugs on the whole territory of the airport which can be used for charging the devices you are traveling with.
There are offices and salons of Beeline, VivaCell MTS and Ucom mobile operators located both in the arrival hall and on the entrance from the baggage claim area. You can easily use the services of mobile operators just presenting the passport to conclude an agreement for the provision of services.
Also, next to the gates in the Departure hall you can find a desk of "Tvoya Svyaz" where you can get SIM cards available only throughout Russian Federation.