Ok. you are on the right path. When you import the file, you need to tick the manual orientation checkbox, as such.
You will then get a massive mess of bones obscuring the model. To fix this, make sure you have the armature selected (it will say 'Hips' in the lower left of your edit screen), and click the object menu(looks like a little man) , then click Stick, B-Bone, Envelope, or Wire. This will give you an edit image like so:
Once you have that done, go into Pose Mode and select the Head bone. It is this one.
Press Shift S and choose 'Cursor to Selection' in the popup. Go back into Object mode. If you don't want to see the skeleton anymore, push H while it is selected. You may now start creating your model. Do NOT MOVE or RESIZE your model in Object mode. Only make changes in Edit mode, or your origin will move and your model will export wrong.