in theory you can also send medical AFTER the 485, but from all the info I read on the internet, you better hold on to it until your interview date. With only two weeks left, I am not sure they would have time to schedule the interview before October 11. I-485 may be submitted without the medical report with the intent of taking it along to the interview or responding to an RFE should one be issued for the medical report.
2. Again, form I-485 cannot be filed online.