> 3. Is there a way to open a database (.FDB file) that is in a folder

of a drive in a client PC (not in the server)?

Gustavo,

The Firebird database must reside on a file system under the direct
control of the Firebird engine. So if the database is on the client
PC's hard drive, the database engine controlling that database must
also be on the client PC.

Fortunately for you, Firebird Embedded has a neat trick up its sleeve.
If it gets a TCP/IP based connection string (eg server:mydatabase), it
acts just like any other fbclient.dll or gds32.dll. (see ReadMe for
more details). So if you used the embedded engine in place of the
standard client library, you can connect to the remote server
(emulating a standard client) and you can connect to the local
database (using the embedded engine).

Adam