Aside from the horrid formatting (e.g. spaces used to align text instead of paragraph centring), your document has a mix of content controls and formfields. You should use one or the other - they're not designed to work together and can behave strangely when combined.
As for replicating the dropdown, presumably you want to replicate the entire row. For code to do that, see:
https://www.msofficeforums.com/word-...word-form.html
As for the shading, the dropdown in the newly-added row should have the same 'on-exit' macro call as the existing row. So, provided you code your colouring macro to work with whatever dropdown it's called from, you should get the same shading behaviour. The code in the link contains comments & code for auto-numbering the formfields (assuming there's only one of a given type on the row).