Aussie F/A-18 Hornets are in 'preservation storage' with Boeing Defence Australia paid to keep them in some sort of sellable condition. Same thing is happening with the ex RAN MRH90s. It is costing Australia money to keep the Hornets, might be smart to sell them to Ukraine in this crowd funding scheme being talked about.
Its the buying thing that is different.
If the US blocks sales of its fighters to Ukraine, Russia wins, because they will be forced to buy non-American and that is a small pool, and increases the value of Russian (and French/etc gear which is still heavily reliant on US tech) as its proven to be less likely to be sanctioned and there is more demand for it.
There is a more at play than Ukraine here. India has some big procurements, as do other non-aligned nations. US slapping restrictions on gear so that even if its a good idea and everyone agrees, it can't happen, is bad. Bad for US sales.
The RAAF needs these planes gone. They need to be disposed of, now.
For active personnel definitely shorter conversion times. When all said and done all you are doing is teaching a bloke taught how to handle a Holden how to handle a Ford (over simplification but generally that is what it is), but likely longer times for personnel out of the service so knowledge, muscle memory etc can all be refreshed
Rating for aircraft, isn't like a car, its a whole different thing. Its like comparing a motorbike licence and a 125cc and a b double articulated trucks with 21 gears. They move on roads, but that is about it. Everything else is different.
However, late mig to 1990s NATO aircraft isn't that hard. People exist who fly both aircraft and can maintain both aircraft. In multiple countries. The bigger issues are things like Ukrainian pilots and aircraft engineers that speak perfect English, and people who have the knowledge who speak Ukrainian/Russian. Not huge in Spain/Australia. But can be found in Finland, Germany. But loyalty and clearance are going to be issues perhaps.
The other issue is the F-16 Mafia. Those that think the F-16 is the only aircraft that can possibly do the job and that the F-18 is not good enough. I don't believe that is the case. The other issue is will Ukraine be able to have a unified fleet. They seem un-interested in a hodgepodge fleet like they got with tanks, with M1, Leopard, Challenger, various Russian gear, all in a mixed force logistics nightmare. Ukraine want at least 100 aircraft. A single sell of 36 is a big step toward that. But is it enough for useful capability from the get go?
But there are other issues, what weapons, and from whom, for how long, how to coordinate efforts.
This internet/cybersecurity fellow, also is curious. Deals aren't run through single people.