Yes, Toronto Pearson is in Mississauga. Who knew. Does anyone know what "Toronto AMF" stands for? I suppose it indicates that its not actually Toronto. Strange regardless.
Regarding the numbering scheme in Mississauga, it is very easy to follow and I enjoy it. On North-South streets, the numbers go up as you go north, so at Lakeshore its 1000, at QEW 2000, Dundas 3000, Burnhamthorpe 4000, Eglinton 5000, Britannia 6000, Derry 7000, Steeles 8000.
So for example, my house number is 6178, so that puts me just north of Britannia.
On the other hand, the East-West numbers are a little more confusing. Hurontario is the starting point, and they go up moving east and west, and every street that crosses Hurontario is divided into E and W. But the numbers don't go very far in either direction, maybe up to 3000, I'm not sure. I know it goes up to around 2500 around Erin Mills Pkwy in terms of the west, and up to 2000 in the east around Dixie. So if your address is anything up to 3000, its not as informative. Regardless, in subdivisions, your house number will follow one of the two schemes, whether your street is a N-S or E-W street. My street is N-S (6000-6200), and the two streets that connect to mine are E-W (around 1400-1500). Mind you none of these streets follow any sort of grid, so its somewhat arbitrary sometimes.