I have some questions regarding generating keys for ssh access:

(1) Supposed there are two computers running ssh server service and I have generated a pair of key files on computer A and copy the public file to computer B. Is it true that this is only a one-way key: We only gave computer A permission to access computer B, not gave computer B permission to access computer A? If I now want to ssh from computer B to computer A, must I generat another pair of key files on computer B and copy the public file to computer A?

(2) If I would like to connect a single local computer to several remote servers, is it to generate a common pair of key files only once on the local and copy the same public file to the remote servers, or to generate different pair of key files on the local for different remote servers?

(3) If I would like to connect several local computers to a single remote server, when copying the public files from different local computers to the remote server, is it to combine them together into a single authorized_keys file or store them in different authorized_keys files?

(4) If there are several servers shared the same file system by, for example, NFS, how to generate keys and arrange the key files for accessing from one server to the other? Also how to still generate keys and arrange the key files for a local computer to access anyone of the servers?

All the machines above are Linux.Please provide examples and commands in your reply so that I can better understand how to solve the problems.

Thanks and regards!