Use e.g. "dpkg -l openssh-\*" to see if it's installed. Services installed without running are harmless.
(1) Yes, /usr/bin/ssh is provided by openssh-client.
(2) You need an outgoing connection to access a remote server.
(3) The ssh server has port specified via e.g. "Port 22" in
/etc/ssh/sshd_config. Client specifies that port via the -p option
or a Port line in ~/.ssh/config for the specified host.
pgpGr_xoeZSI9.pgp
Description: PGP signature
