text vs varchar(n)

Couple of questions:

If ones sets up the db to be UNICODE, does that also apply to the 'text'
type?

Which is faster read and write, a table with text or varchar types:

create table text_table (
id   bigint,
value text
);

or

create table varchar_table(
id bigint,
value varchar(1024)
);

Why would one every use varchar(n) instead of text (aside from non-sql
standard)?

Thanks.

Richard