Conditional Formatting with Form Controls. I'm stumped

I've been tasked with making a quote form that is in line with our catalogs and is a little easier to use. We want to be more efficient and less informative with our quote form...meaning we want to be able to quote based on pictures and not on complex part numbers and mile long item descriptions.

I am basically trying to build a would-be shopping cart in excel and in order to do so...I'll need some conditional formatting and form controls...and be able to use them together.

This is what I'm working with:
quote_form.jpg

Working from Top-Bottom, L-R, here's what I'm highlighting with my arrows.

Catalog: A drop down menu with either "-", "Building Products", or "Retail Environment" as a selection. Already got this one...but thought I'd point it out to make understanding easier.

Category: Needs to be dependent on the selection above. If "Retail Environment" is selected, the options (found on another sheet in the workbook) shown need to show. I'd like to have this be in the form-control format I have it in. I'd like for the listings to change when I select the other catalog...and appear blank when "-" is used.

Item: Again, contingent on the item before it. When Category = "TV Display", Item (found on another sheet in the workbook) should show options available in that category. When I switch to Kiosk, i want to see my kiosk options.

From there, I'd like to have a drop down for Color, a scroll box for quantity, a displayed price that equals the Price Per Unit (found on another sheet in the workbook) times the quantity. From here, I want to be able to "Add" and the information take the next available line in my cart (shown in orange).

I know this is too complex for me to work out on my own...or even with the help of google (I tried)...so I've turned to you guys.

Thanks in advance.

And if this is unachievable...say so. It's about the most user friendly thing I could come up with...for everyone other than me...since I'm making it. If this isn't practical, I understand.

I think i'll start off a little more basic in my request for help. I've re-read my original post and I'm asking for some major assistance.

Let me start over with this:

Can you use form controls and data validation together? If so, can there be multiple levels of contingencies in multiple categories?