Getting Value From Next-highest 'header' Row

I have a worksheet that contains a number of rows. [Thank you, Captain Obvious!] These rows are logically grouped to represent a series of "items", with each item having one or more rows (with a "header" row at the top). The rows for a particular item represent different types of information about that item, and therefore make use of different formulas based on the row type. Due to the relative complexity of the formulas in these rows, I am creating a series of row "templates" from which I can copy and paste every time I want to create a new item or add rows to an item. As such, I am trying to avoid direct cell references to different rows, as these would easily get messed up during cut and paste. Instead, I am trying to limit myself to various lookup functions (e.g. OFFSET, MATCH, etc...) that will work regardless of where a row is added.

In order to accomplish this I am using a "key" column to group all rows for a particular item together. Until now I have had to type in the key value for every row for a particular item. What I would like to do is to only have to type the key value in the header row, and have a formula populate the key value in all subsequent rows ... until a new header row is reached, at which point the new key value will be used. Take a look at the following example: ....