If you are used to the weather temperatures in Bama, be sure to check out the long range forecast for Toronto on the WeatherNetwork web site the week before you leave, to decide how to pack.
I have a friend who married a gal from Bama and moved there where she set up her practice (eye surgeon). He found a job with his skill set quickly.
He never sweated so much in his life the first summer there he related to me, and that was with work, home and the car all fitted with A/C.
We consider a high of 6-10C a nice spring day if the sun is out, after a winter of cooler cloudier times.
If you are planning a few early morning shoots, down by the water, then for you a pair of long underwear and a set of layered warm upper coverings that cam be progressively stuffed to a back pack may not be a bad call on some mornings.
The other thing is that the rain here in the spring makes you both wet and cold. Not at all like the rain where the weather is warm. Bring a rain coat; it will be a good wind breaker at the very least on early morning outings.
I lived in for a time sub tropical Australia, where the regular evening rains were a relief to feel after the day's heat.
If you are looking for a neat half day trip and are up for about 10km of walking, going out to the end of the Leslie St Spit - now called Tommy Thomspon Park is a nice change of pace.
Still part concrete lake fill site by weekday, but the idle sections have seen nature take over, and that is a pretty quick green contrast to so much of downtown.
I am pretty sure the Leslie bus gets pretty close.
High Park can be nice in the spring.
The Distilery District I find pretty photogenic.
Nearby, the underside of the elevated Gardiner Expressway, which is Lakeshore Boulevard, still a major traffic artery, gives a different look quickly, just one short walk under the railway corridor.
Yonge Dundas Square on a friday night is always a pretty good street shoorter location unless it is pouring rain. Right on one of the subway interchange points.
Union Station has nice architecture. Bring fast film, lens - not all spots that bright inside. Again, another major public transit interchange point.
If you are wondering, I live in the city of 600,000 next to Toronto, where your plane will be landing. About a 20 minute trip downtown in light non-peak traffic.