Long was given his chance up front because of Kevin Doyle's knee injury, while Birmingham midfielder Fahey came in for his first competitive start after Liam Lawrence failed a fitness test.
And both played their part in the 1-1 draw, with Fahey sending over the free-kick which resulted in Sean St Ledger giving the visitors the lead, while Reading forward Long was a constant menace to the Slovakia defence.
Trapattoni cast doubt over Robbie Keane's international future while he continues to be a bit-part player at Tottenham, and a number of the Republic's other key men are nearing the end of their careers.
So the emergence of new talent is particularly welcome for the Italian as he looks ahead to the resumption of the campaign next year.
Trapattoni said: "I thought Shane Long and Keith Fahey played great games. For the future we can have confidence in them knowing the options we have in the squad. We have time in the future, our next game is a friendly. I can maybe play one or two other young players and we can start the qualification again with more confidence."