Well, apache has to listen for something somewhere.
So, yes, you have to at least put where apache needs to listen in http.conf, otherwise it won't.

You can use IP address, but a fully qualified domain name is preferred, as it easier for others to remember.
And you should be able to access apache once you have configured it by typing
http://ipaddress. Just the
ipaddress without the
http:// may not work. Port number is not required unless it is different from port 80, as 80 is standard for http.
Hope this helps a bit.
What OS are you running Apache with, BTW?
Cheers
Mick