CADPAT15, have you even started the process to join the Canadian Forces? Are you of age to join up? Wondering since last year you were talking about cadets. If you wish to join JTF2 keep that in the back of your head for awhile until you get into the CF and do your courses to the best of your ability.
From memory by reading off their website, Signal Operators can be employed as both Support and Specialists. Supporter and Specialist roles are similar but different, Specialists AFAIK directly support the Squadrons/Assaulters and won't be too far behind them. As for involvement in combat, that is a long ways away for you, no need to worry about that now. Who knows what future missions there may be - they may or may not involve combat.
For the physical side, if you want to be a specialist you are going to have to be in good shape(as well as knowing your job/kit). I believe if you wish to join as a Supporter you must do the Canadian Forces Express test, but if you wish to join as a Specialist you will have to do the Coopers test and score minimum 75 points.
Again, focus on the short term right now, getting into the Canadian Forces as ACISS - Army Sigs trades all merged into this. Complete your BMQ, BMQ-Land, driver course, DP1 and be posted to a unit and learn as much as you can. To join CANSOF you will need 2 years in before you can apply, use that time to learn your job, work on physical fitness, etc. During the year CANSOF recruiters will visit the bases and give briefings, attend one and learn about the unit, and what they are looking for. As well there will be CANFORGENs released about CANSOF recruiting. Also you can contact their recruiters through email. Don't expect them to tell you everything you want to know over the phone/email/in person, some things you won't find out until you get into the unit.