5150 Spectrum Way? You’re taking a class in the office park south of the airport? And you’re staying downtown? Oh dear.
Your class is about twenty to thirty minutes’ drive from downtown, assuming no traffic problems. Go west on the Gardiner Expressway, north on the 427, exit at Eglinton Avenue. Be sure to get into the collector lanes on the 427; if you remain in the central express lanes, you won’t be able to exit at Eglinton.
Turn left onto Eglinton from the exit, and head west. You will pass under some bridges. Continue west past Renforth Drive. You will enter Mississauga. Spectrum Way is the second or third cross street past Renforth. The Hewlett-Packard/Agilent building is a landmark in the forest off to your right.
If you go down a hill and cross a bridge over a creek, you’ve gone too far. If you pass a vast postal sorting plant on your left, you’ve definitely gone too far. And you’d be in the neighbourhood where I used to work. 
You can get there on public transit, but it is not fast. You would have to take the TTC subway to Islington station, then pay another fare and take one of the Mississauga buses that go along Eglinton or Matheson Blvd through that office park. No GO buses or trains go anywhere near the location.
The TTC costs $2.50 for a single fare; if you are going to be using it four or more times in one day, it’s cheaper to get a day pass. The day pass is not valid until after the morning rush though. Mississauga buses cost $2.25 for a single fare.
The #27 bus from Islington goes along Matheson and crosses Spectrum Way; the #17 bus from Islington goes along Eglinton Avenue and crosses Spectrum Way. Mississauga Transit has a PDF map of the area.
As for restaurants in the area of the course, there’s not a lot. There are some lunchtime restarants, a McDonalds, and so on, but the area pretty much empties out at night, so it’s limited. If you are lucky enough to be in the HP building, I understand it has a decent cafeteria… but for evening meals, go downtown.