Pulling drop-down menu values from another sheet

I am trying to create a web-based order form. The item that people would be requesting is seperated into categories and then numbers.

E.g.

Category A

          Item #0001

          Item #0002

          Item #0003

Category B

          Item #1001

          Item #1002

          Item #1003

          Item #1004

I have these items listed in another sheet and would like customers to be able to select a category, which would then pull up the subset of items in that category (i.e. select category A which would then allow you to select from items #0001-0003.) We have 30+ categories and 700+ item numbers which is constantly being added to, so to have to scroll through all of those without selecting the category first might be a bit cumbersome, not to mention time-consuming when trying to add all of these to a drop-down value menu.

1. Is there a way to select a list of items from a list of categories?

2. Can Smartsheet pull these values from my other sheet?

I know that Excel is capable of this, but I didn't know if there was a way to do it in Smartsheet.

Thanks!