Hi Usher9387!
Nothing is a dumb question here..Everyone went through on that stage that we don't know anything at all that is why we are all here to help and support one another. I have followed all your post and it seems that you haven't received a concrete answers to all your questions. Okay, to further clarify everything to you the “decision made” under the sponsorship application status means you are approved to sponsor the principal applicant, you should be receiving your sponsorship approval letter by now (SA) but take note some don't actually received SA and just automatically goes on the next stage which is the processing of the permanent residence application of the Principal Applicant. It's a case to case basis.
Though I always check my ECAS as well I don't really depend on it since according to senior members it doesn't really show or tell you the exact status of your application. And on some cases they don't really update it especially on the stage 2 processing. You will find out that your papers are transferred once you received your SA then AOR2 will tell if the VO-Australia receives it.
It is okay if you haven't done your medical yet you can do it once they request it to you or you can make an upfront now and then send them a copy of it to cut the delay. But it's totally up to you if you want that or just wait for them to request it to avoid re-medical.
I hope I gave you a much clearer perspective now