1. invitation letter
2. T4 is for your personal tax return for year 2001, you should keep the original for your copy, no nee to submit if you already have pay stub and employment letter.
3. CCRA's notice of assessment for your privious tax year.
4. Your parent do not need your notarized birth certificate, instead, they'll need notarized parental certificate.
5. BTW, where do you submit your application, BeiJing or Shanghai?