date & time

Hello,
Can some one please tell me how to set the date&time in the PostgreSQL
system?
I try to use date('now') and time('now') to keep tract of the data and
time when the data is inserted or updated. When I use sql " insert into
table (data1, date_chg, time_chg) values ('abc',date('now'),time('now'))
" to insert the date and time data, the data successfully inserted but
when I retrive the data, it shows that the date and time is always "
01-01-2000 " and " 08:00:00 " , now is of couse not year 2000 and the
time is also not 8 o'clock. Why? How should I correct this?
I am using PostgreSQL in Linux system, and the date & time for Linux
system are correct.

One more question, what is the common data type for storing address?

Thank you very much.
Regards .... lch