bytea encoding

Hi

I am doing some feasibility research and have some questions about
bytea:

1. Is the byte stream (or byte array) converted to bytea on the database
side or on client before sending?  (My client is using the
postgresql-74.213.jar).

2.  If client does the encoding what will happen if the database
receives information that is already in bytea?  Will it recognize that
the data is already in bytea?

3.  Is there a way to convert an array of bytes into an array of bytea
values?

Thank you,

Jesse