The databases will not be stored in one particular location.
Oracle binaries which include thses utilities will be in one location and datafiles thats associated with database will be on different file systems.

If Oracle binaries or in your unix userid path, you can invoke thses utilities by typing in at the prompt. Otherwise it will be in the bin directory of oracle home.

That syntax is right. But make sure you have to use the right version binaries to export that version of database.*for 805 version use 805 exp)

Use unix 'find' command to locate the executables.

$find / -name 'exp' -print

If you further want to use any options of exp type in @ the prompt

$exp help=y