Just attach a blank document or cite:
As of October 1, 2023, you no longer need to get an upfront medical examination before you submit your application for permanent residence through Express Entry...
It's not a glitch, it just doesn't take into consideration that you have already been invited.
There's a public policy for that https://www.canada.ca/en/immigration-refugees-citizenship/corporate/mandate/policies-operational-instructions-agreements/age-based-requirements.html
1) Your highest degree.
2) No. just a photo.
3) Both ways are good.
4) Nice to have.
5) Employment letter, paystubs, T4.
6) Yup, as long as it doesn't impact your score.
3 months is quite a long stay, especially for the first visit. They should have a very strong profile to be approved: personal funds (a lot), ties, travel history, otherwise I would better opt for super visa.