Make an App that accepts add-in's

Hi :wave:

I'm working on a project which has many functionalities. Although, my app will need to have more and more functionalities. I was thinking... can i make an app (like WinWord, Excel, VB6, etc...) that will accept add-in's?
I don't want to re-compile an entire project just because, for example, I had a new function to export data to file.

My questions are:
1st - Is it possible?
2nd - If so, how complex can it be?
3rd - What do I have to change in my Main App to accept the addin's?
4th - How do I make an add-in and "install" it on my app?

I hope this thread may be usefull to all comunity.
Thank you all.:thumb: