Plans for Big Site, but lacking experience... Few simple questions

Hello. I’m just barely learning MySql and PHP and I have plans to start a retail-style business with my dad. I want to make a website that will display our inventory, has a shopping cart, and a search engine. My questions right now are kinda basic:

I’m thinking about making one large database to hold the product name, description, picture url, ect… And since I have a little experience with XML - I was thinking of using PHP to produce one large XML file for everything in the DB. Then I could easily create pages in flash to show 12 items of the inventory on each page (have their pictures and descriptions, etc.), and the only thing I would have to change for each page would be my action script to pull information from the XML. More specifically, the first page would show items 0 to 11, the next page would show 12 to 23, and so forth…

My question: is this a good way to do this?

If not, I need to find some way of using PHP to show different items for each page. I mean, like I said before, “the first page would show 0 to 11, the next page would show 12 to 23, and so forth…” Also, I’m willing to create pages using mainly PHP if necessary (like instead of all flash).

Any thoughts, codes, urls to tutorials, or anything that may help me out?