Welcome to the forum,
1) Use to T4 and existing paystubs, by the way there is table showing how much minimum salary you should have to sponsor a person. So try getting job soon. Paystub, T4 and Tax receipt print-c form does the job for your banking information. Thus you don't to show bank balance.
2) IELTS is required if she is coming as student. As sponsor NO need to.
3) Yes get the appointment for physician and get medical done asap. Also apply for police clearance certificate asap. Both things need to attach in sponsorship file.
Suggestion: Please go through sponsorship guide before applying, if you miss any document, each missing document will delay your file from being processed. Average time for file processing takes 6-8 month. Missing document is one bad reason for further delays.
Best of luck, Hope you guys join soon.