You will find MinBowl eatery on the ground floor. The building has three doors, you can enter any of them. Please walk past the sitting area and the receptionist. You will see three small couches at the very back. Take a left at them and you will find elevators.
Bus number 15 departs from the Viru Shopping Centre bus terminal, station number 2. You should get off at the "Dvigatel" bus stop (the one after "Ülemiste jaam"). The bus stops in front of the building located at Lõõtsa 6. Bus number 15 stops also on Tartu Road. So if you come from the Tallinn Central Bus Station, walk to Tartu Road, then take a right and continue up the hill to the stop "Autobussijaam".
From 6 AM to 10 AM and 3 PM to 8 PM bus number 45 travels from Õismäe to Ülemiste city via Mustamäe and Nõmme. Get off at the "Dvigatel" bus stop (the one after "Ülemiste jaam"). This bus stops at Suur-Sõjamäe Street.
Online bus schedules can be found here: http://soiduplaan.tallinn.ee/#bus/en