Try to get your experience letter in format specified by CIC.
You can also see what police certificates you would need and see process for them.
Regarding Medical , it is somewhat confusing Even after getting ITA it is called upfront medical test since you do medical before submitting your application therefore the term "upfront"
I went to designated clinic for medical test and they don't need to see ITA I just mentioned term "upfront medical for Canada Immigration" and it was smooth. so it is possible to get it done before receiving ITA as well as clinic never asked for any document/ITA from me.
