Timothy Normandin is detained on suspicion of criminal trespass
Pop star is accompanied by songwriter David Foster
Pair perform Grande's 'Love Me Harder' and Bieber's 'As Long As You Love Me'
Singer names Imogen Heap among influences days after she falls over on stage
The singer was expected to travel this month to promote her album 'My Everything'
Duo performed 'Love Me Harder' collaboration as season 40 of US comedy begins
US pop star is believed to have been a victim of major hacking campaign