Our favourite campsites at Glen Rouge are 27 (first choice) and 29. For 27, you need to come in with the front of your trailer facing the river, otherwise the electric will be on the wrong side. The young people at the entrance do not know that. It is a 50 amp.
Depending on what part of Toronto you need to be, the same outfit that runs Glen Rouge also has other campgrounds:
https://trca.ca/activities/camping/
I am not familiar with the other ones as we always stay at Glen Rouge. This is because we visit friends and family in that area.
As for fishing, sorry we do not partake in that sport so you are on your own there.
You have to check the website or call the to find out when the reservations open up. I called in the winter and found out. This spring I was able to reserve on March 18. Because there is not a lot for camping in the Toronto area, you will need to reserve. Mind you, we did see some empty sites when we were there in early July. We were told that on weekends the place is full. It is very popular with the locals.
I don't know where you are coming from, but if you are coming from the west then you have to cross the city. If you are coming from the west, let me know and I will give you tips about that.
The GO train takes you right downtown to Union Station. To get parking at the station, keep in mind that the commuters quickly fill the parking lot. The "remote" lot, not that far, is usually good. To find that, take Port Unon Rd. right to the end, there is a traffic circle, and you see the lot right there on the east side of the circle.
If you need any more information, do not hesitate to ask. We used to live in Toronto many years ago and are still fairly familiar with the place.