It’s the day following the order that starts the counting. But, file earlier if you can for safety.

More information is needed to determine what has occurred and what is sought to accomplish. You may post another question with more information to...

You could file a motion or object and wait for them to file a motion.

Get online and search the many resources. There are also books that explain civil procedure.

You can amend once before the defendant files anything, otherwise you can file a Motion to amend.

It is not too late to subpoena. You can also try to convince them to appear voluntarily (but do serve the subpoena also).

Yes. Many courts are now continuing remote appearances for many appearances.

This is a constant issue in cases. You can request the defendant attorney to stipulate to a tolling agreement. Or, file a lawsuit and request...

You could be subpoenaed but it sounds like it would not benefit either side.

If there is no Judgment yet, then a reminder of what the judge said may be all that is needed.