Background: I am tasked with rewriting a 9.3 ArcMap solution based upon a VB6 implementation using an application extension and several forms. The interface to ArcMap is that this solution needs to find a running instance of ArcMap with a specific map in it and then selects features in a layer in that map. This will be redone for ArcMap 10.2 using C# and VS2012. I am new to ArGIS stuff and in someways new to .NET/COM development. Yes, I know I am in deep. :)
My Question: I have read the documentation till my head is spinning - such a mixture of versions and FWs between both ESRI and MS. I cannot decide upon the proper approach. I feel that I should use a COM based application extension as the heart of the re-write, but I have also seen mentioned an Add-in application extension. What I don't know is, can I use an Add-in application extension instead of a full blown COM based one? Do they have the same abilities, or as in Add-in application extension more limited than a COM one? I have seen information that points to add-ins not being as capable as COM based solutions but this seems to be lessening with each release. To be honest, I don't even know if an Add-in application extension is the same kind of thing as a "traditional" application extension - and I can't find that out from the docks, which frankly, suck.
Additionally, if I AM able to go with an Add-in application extension, how capable are the dockable forms that apparently are part of Add-in land? In the VB6 Forms that I am replacing, database work using ADO to Oracle is being done. Would I still be able to do that with these dockable windows?