It's because UAE is not eligible for SDS and non-SDS doesn't require GIC. And yes, it must be from main applicant's account, else, it will be rejected.
Yes you do, in case you get deferred and the fee increased, you don't have to pay that before your arrival tho
By the way, are you in Fanshawe college?
Retake medical as soon as you can and send the E-medical sheet via a webform. The processing time varies so have a copy of the sheet with you and hope for the best.