With most deals, selling clubs will want other buyers to come in for a bidding war, and those get the most active near the end of the transfer window.
All clubs could negotiate before the window, if it were of benefit to everyone.
I don't know what you're talking about. Sorry.
Clubs will hold out for the best possible offer on their assets. And may decide not to sell if they don't need to. Not sure how this is difficult to grasp.
Coutinho has a Portuguese passport, and worked in the UK before. He's been through the process, probably still has the prerequisite permit. I don't know about Azmoun but hiring foreigners in the UK has not got any easier over the last few years.
I'm going out on a limb here, but there's no way an Iranian player would be granted a work permit quick enough for the next game. Probably not the one after either.