It is the individual member states that will decide when and to whom their borders will open.
Not true.
If there is a Schengen-wide agreement to keep non-EU/UK/EEA nationals (with some exceptions) out, then this agreement is binding to all Schengen members.
Of course, a Schengen country may apply an even more stricter approach. But it is not allowed to deviate towards a more liberal approach.
With the current state of the Coronavirus in the US, the EU will keep its borders shut.