Sure, no problem.
On the first machine, with 12 threads, and 256k coinage (via 256K bbp with 1 day age), yes, it can only mine 1 block per day, because if it finds a block, its coin age would be zero and slowly rise for 24 hours, and then be applicable to mine again once it breaks 256k in age again.
And yes, each thread shares the same ABN.
On machines 1-4 with the shared wallet, all 4 machines could only mine 1 block per day, and all four would simultaneously lose all the coin age.
Yes, 1 thread needs 256K of coin age also.
Thanks. So for 1 machine with 12 thread, it needs 256k*12 ~3M bbp for full running. If one block mined in 1day, only 11 threads will work, one thread will be banned by ABN.
No, it just needs 256k weight for the machine, for all threads to run.
If any thread finds a block, the ABN weight in the wallet will drop, and all threads will stop.