To be accepted into university, you have to keep up your overall average in your second semester. So if you have a lot of failing grades in second semester, those will hurt your acceptance average.
February - March, 2017 – Applicants presenting a minimum of 3 final or 6 midterm Grade 12 U/M courses will be considered for admission on a rolling basis (applicants must have 6 Grade 12 U/M courses completed or in progress, including program specific requirements).
April 2017 - Applicants will be reviewed again upon receipt of second semester midterm grades
(offers will go out on a rolling basis as grade data is received, until May 15).
As for switching between entire faculties, that's not as easy as just deciding to switch from Humanities to Science and jumping into Science second year. Since it's an entire faculty switch there is more involved and factors to take into account, including admission requirements into the program you're switching into.
As per the website:
"If you wish to switch to a different program in the faculty, make sure you first qualify by checking the admission requirements of the program in question.
Please go to your Mosaic Student Centre, choose ‘My Academics’, and use the ‘Program/Plan Application’ to submit the change.
It is always recommended that students first discuss a program change with their advisor to ensure admission requirements are met and program requirements can be reviewed.
If you wish to switch to a program in a different faculty, you need to be in contact with that faculty office to discuss requirements and the process for changing."
Also, in first year Humanities, you don't specialize until later in second and third year. Your first year courses will be pretty general and a whole mix of things in Humanities, including electives. Only in 2nd and 3rd year do you start focusing on a specific part of humanities - communications, multimedia, english, history, etc. etc. lots of Level II programs you can then specialize in for your B.A. ...or you can minor in one so you have multiple.
As per the Humanities website:
"Admission to Programs in Level II
Students entering the Faculty of Humanities take a general Level I program. They apply for entrance to a specific B.A. or Honours program at the end of their first year and must meet the requirements for that program. Eligibility for degree programs is governed by the student’s choice of courses and academic performance in Level I. Information on the academic average requirements for programs in Humanities and the Social Sciences can be found here: Program Entrance – Academic Requirements
Note that Multimedia is a limited enrolment program. Entrance is competitive and is based on academic achievement, so the stated minimum requirements may not be sufficient to guarantee admission to the program."
So I would stick around in Humanities for at least 2nd year before you decide if it's a good fit because you won't be able to know until you get into the more specialized programs.