1) All checkin desks really will be closed across the whole network ?
Probably not
2) Those without EU / North American passports will not be permitted to fly with Ryanair to/from the UK and Ireland ?
unlikely
3) Some checkin desks will actually be retained at airports, but they will just have a very expensive fee to use them - paid only by non-EU citizens ?
Probably free to Non EU - a charge for EU
4) Ryanair doesn't care about the potential immigration fines ?
They do big time - reckon their online checkin has a backdoor into false passports so Police / immigration see who is using them
5) Checking of visas will be done at the gate with little or no time for sorting out any queries ?
In most countries flying from Schenegn to UK / Ireland there are security/ immigration checks anyway.......issue not relevant across most of EU as if there automatically assummed you have Schengen Visa........damm never though about that which is why it will be a winner as no need to check anyway across most routes.