Newbie questions on openssh

[Eduardo M. A. M. Mendes]

Hello
    I have just installed openssl on my lab I wonder whether an exprt
could help me with the following
queries:

a) slogin xxx.yyy.zzz for the first time requests a yes or no answer
regarding trusting the host.  When
I answer yes, what does it mean?  Are all connections from now on
secure?
b)  Is there a script that automatically slogin and send the password
for  an user?

Thanks a lot.

Eduardo