Helen,

Some quick answers:
GB per month - this is the traffic that travels in and out of the hosting server, such as people viewing your site, emails going back and forth, and you uploading your web pages. It's worth noting that the MAJORITY of your traffic will be outbound. For example, you upload a picture to your site - that's inbound of say 50kb, but then when people view that picture on your site, that's 50kb outbound each time it's viewed. So unless you're expecting to receive lots of big emails yourself, then look mainly at outbound traffic allowances.

Payments - Some places offer discounts if you pay a years worth of hosting up front, but usually it's non-refundable, and you can be locked in for that year. We find most of our clients like to pay monthly, and they can leave any time they want.

Building your website - depends on what you want really. You can do really easy template based sites (we provide SiteBuilder for free with all our accounts), or if you need a shopping cart, there's plenty of those around too. We install osCommerce for free, but this usually requires a bit of work customising it to how you want it to look, but it's an easy shop to operate. There are plenty of shopping carts out there tho. X-cart is meant to be really good.

If you are setting up shop, you need a database included in your hosting, and you'll need to look into SSL certificates etc to secure the site.

Basically, work out what is going to be on your site and go from there. We usually start people off on our lowest plan, and then just monitor traffic etc as we go to see what their needs really are.

If you want any more info, I'm happy to help out. My email is in my profile

Liz