Questions about CP CN or VIA?

I am currently working in France for a large railway company called SNCF.

For over 4 years, I have been responsible for the maintenance of electrical signalling on railway lines, including numerous safety systems such as level crossings.
I also have more than 3 years of experience in maintenance and repair of trains in workshops, prior to my current role.

My sister lives in Montreal, and I recently applied for a Working Holiday Visa (PVT) in the hope of being able to come to Quebec/Canada to work in my field there.

The key difference between France and Canada is that, in France, SNCF is a single public company, where all the services related to traction, rolling stock, management, passenger services, maintenance, and railway operation are grouped under one entity.

I started researching railway operations in Quebec, and it is difficult to find consistent information on my research.
There is Canadian Pacific (CP), which owns rail lines.
There is Canadian National (CN), which also operates a large network of railways.
And there is VIA Rail, which handles passenger services and operates its own Technicenter for maintenance.

I have several questions on this subject:

  1. Are the railway operations of CN and CP different, or do they run and maintain the same railway lines?
  2. Does VIA Rail own any railway lines?
  3. Which company is responsible for the maintenance and renovation of railway tracks in Quebec and Canada? (I am looking for a job as an electrician technician in signalling.)
  4. Between CN and CP, which is closest to Quebec ?

Thank you for your time dear Train-Service friends ;)
Kind regards.