and lining things up behind the scenes?

The ones entering the portal now are more in need of broad awareness of their availability.

I have no insight, just suspect that's how things would work.

It's also against the rules for any FBS player whose coach didn't leave to actually talk to anyone about transferring because he is under contract......er..on scholarship with his existing team.

So I am sure that neither of those things happen. Because they would be against the rules.

the portal but isn’t picked up by another team? For grad transfers I would assume their career is over, but many have multiple years of eligibility left. Is this a short term influx because of the CoVid year?

this is a created influx because they changed the rules to only have the window open at specific times because the coaches were crying. Once you're in you are in until you find a new team or your old team accepts you back. If your old team doesn't accept you back and you can't get a scholarship somewhere, you are likely looking at either hanging it up or walking on somewhere.

Are student-athletes permitted to converse with other coaches whose teams
they would like to join before entering the portal?

so there is NO WAY that would ever happen.

Because it would be against the rules.