I'm IT degree student and first time dealing with web site. One of my friend is running small private institution and he asked me to make a website for him and it should be hosted in NZ located server.
I'm making it with wordpress and phbb3 to use forums for students.
The site will contains few photos but mainly texts at this stage.
For the forum, some photos and mainly texts as well.

I'm looking at openhost, 24/7hosting and webdrive. I'm not sure some terms and idea, please help me with:

1) How big is 4Gb traffic? I have no idea if 4gb gonna be enough.

2) Since i'm making two sites(wordpress and phbb3), does that mean I have to extra dollars on webdrive?
Their plans only include one website. What does website exactly mean?

And any other webhost recommendation would be helpful.

Thanks