It depends on the network operator whether they allow the Sim to be booked in the 4G network.

Should work, but depends on the network operator or the tariffs booked

Yes, that works. However, you cannot use 5g with this device. By the way, there are no 5g SIM cards. Whether you can use 5g does not depend on the SIM card, but on your supplier and the contract you have taken out.