I think there are two obstacles to learning 3D modelling: the first is understanding, or getting around in 3D space, and the second is the interface of the 3D tool. You already know the first so you are half way there.

Learning the Blender 3D interface can be a challenge since it can be customised so much as to be unrecognisable from one course to another. And by "course" I include the 100's, if not 1000's, of short tutorials on the Web.
Rather than going to 2.7, I suggest leaping straight to 3.0, 3.1, or 3.2 (current). If you want 2.7 because of IM exports then you can do that with Rileyzzz's IM exporter which works a treat in later versions of Blender. See
https://github.com/rileyzzz/BlenderIMExporter
There are some online courses that are free (just Google "Blender courses free") but I have no idea of the quality of most of them. However I highly recommend checking out the free CG Cookie Blender 3.0 intro course by Jonathan Lampel. See
https://cgcookie.com/courses/blender-3-basics-intro-to-blender. The more in-depth CG Cookie courses require a subscription but armed with that course you can probably find other free tutorials that target your particular need. For example, bevelling, and other slice and dice tools. I admit I have been a CG Cookie member for several years.
If you want to export to FBX with Blender then I'm part way through updating my Trainz WiKi "How to export..." page and hopefully it will be up in a few days. The animation version update will follow.