I have been using this for a long time..
Sooner or later this will be too old to use.
It only works writes 2009 (6100) version of FBX but its a built DLL ready to use.
It reads 2015 with no problems.
Just put it in your projects directory and make sure its being copied to the output location. Also.. Make sure you include it with any setup projects!
Here's a link to the DLL and A lot of code. Its in VB.net but can easily be converted to C#.
This code is from a App I wrote and has a lot of subs and functions you will never need. It does show how to build instanced objects and materials and also non-instanced.
Why am I doing this? Because its very hard to get any help with FBX and how to work with it. This code is sloppy but has a lot you can use. It has NOTHING about animations although the FBX wrapper apparently can work with them.