To become a CIC officer, you need to be 18 years of age, no criminal record and be accepted byt a local cadet corps Commanding Officer, the legion, the Army Cadet League and the ACO (Acting on behalf of the RCO).
You need to pass a medical exam and an entrance interview at the CFRC
You need to receive Enhanced-Reliability security clearance (cleared to view up to Protected B documents)
Also within the first three years of joining you need to take a Basic Officer Qualification course and either the Military Occupational Course or Junior Officer Leadership Course for your element, you must also have participated in SHARP, TREES and CHAP training, you now are almost required to have first aid (currently being phased in - a rumour on this one, but not a bad idea)
To become the training officer, you are appointed by the commanding officer. You usually have experience in admin and as a star level officer. Usually LTQ is a good course to have for this.
You cannot be in the PRes and CIC at the same time, what can happen is a member of PRes or Reg Force will volunteer their time with a unit.