I plan on taking 3 courses this summer and I'm just wanted to know how lectures are and is it easier?

Is there class everyday? I plan on commuting from Mississauga so I don't really want to be exhausted all summer

Do I get to plan my own schedule? In regard to time?

Also once I have done term 1 and 2 of summer, can I apply for my second year program? will I be able to get in?

It depends.

If you take a simple course, like first or second year economics, then you will be able to breath thru them with ease.

If you take a course that requires a lot of calculations and plain balls to the wall brute-forcing your way thru piles of sample problems, like a engineering math course or something, then I suggest forget about it. Because they not only go thru topics a 3 times as fast, often ruining the quality of explanation, but also require you to do the same amount of work 3 times as fast, and if you take 3 courses (2 in one term, 1 in another), it will hit your marks hard.

If it's a course that requires a lot of reading on topics you don't really care about, it will also hit your marks, as you won't be able to focus during the day to study properly, and you will most likely only have time during day, as summer school is often all about night classes.

It is easier just because you have all the rest of the day to study for it.
They don't make it intentionally easier than it is supposed to be.
The schedules are set by the registrars.

Many people take summer courses for one of three reasons:
1. The course they're taking is too hard for them, but they still want to get into a med school - taking advantage of the fact that most Canadian med schools don't consider summer GPA
2. They want to graduate early or they want to graduate on time but they don't have enough credits
3. They failed a course which is a prerequisite for the next level course they want to take in the next academic term

To answer your question about scheduling the summer classes are usually 3 hour blocks twice a week. When I did summer school I purposely looked through the schedule to find two classes that were running on the same days. So I had a class from 12-3 on Tuesdays and Thursdays as well as an evening class from 7-10 on Tuesdays and Thursdays. I drove home (to Chatham) for every weekend and did very little homework at home, but during the time that I was up in Hamilton from Monday night to Thursday night I used all of my time to study and practice. I really enjoyed the pace of summer school and loved the 3 hour classes, especially since I had nice profs who would let us out early most of the time. It's a good experience to try.

Once you finish summer school you will not be eligible to apply for your 2nd year program as that's only done once per year in the spring, meaning you'll have to reapply next year.

What people usually do is apply to their program of choice when they are eligible and then take summer school and if they pass/score high enough on their required courses they get in.

You can choose the classes you want (so long as you meet the prerequisites and it's offered), but you don't get to choose when they happen. The tentative schedule was linked to in another thread:

https://adweb.cis.mcmaster.ca /mtt/U201405.html

Depending on your work ethic and the course, it can be easy or a pain. Classes tend to be Monday & Wednesday; Tuesday & Thursday. Three hour lecture blocks, sometimes with a tutorial added to it, making the block four hours.