Follow the first couple of repro steps here to create a Visual Studio Tools for Office - Excel Add-In.
Skip the last step about the calender control.
In the Excel AddIn Project > add a Ribbon Bar and Button and you can
invoke methods to collect the data via http and refresh the workbook.
Everything in VSTO is pretty much the exact same way you would do it
in VBA but in C# syntax.
Extend Your VBA Code With VSTO
When it comes to deploying you should use a Setup Project and it will create an MSI.
If you have a App.Config file be aware when deploying you need to set the setup project to add a registry key: https://stackoverflow.com/a/10525693/495455
I highly recommend this blog for tips on better VSTO memory management via .Net code:
http://jake.ginnivan.net/