Creating add-ins in C#? Simply use the templates!
I'll just start out with an easy tip here that I think could be helpfull to many who want to create add-ins for Office Accounting (and yet so easily missed)
If you install the Office Accounting 2007 SDK it will include a couple of templates that you can use directly in visual studio.

If you pick the OfficeAccountingAddIn template you will be able to chose between some of the types of add-ins that you can create in Office Accounting.

And the basic Solution with driver registration, driver info, and other basice will be generated for you...

I like, I like!! By nature most developers are fairly lazy, I know I am! ;o) so if I can get free code like this I take it.