Huh, for me when scene settings in Blender are set to metric (and scale set to 1) the units actually end up being the same! If you’re not using Blender 2.75 or above that might be the issue, otherwise I dunno what is going on. But, scaling within Blender is definitely the way to go if you need to.
Oh, and one thing you might do is apply the scale (ctrl+a) after scaling the objects, I don’t know if that still causes issues but it had for me in the past.
Now onto your other question!
Cheers,
-Noah