@SomethingRidiculous, please stop.
Alright let's get serious bitches, it is true that the textures should NOT be in jpg format jpg is not supported properly for in-game model texture usage as HPL is made to work with Direct Draw Surface (DDS) and they need to be POW2, HOWEVER.
1024 X 512 is just fine, that is a POW2 texture, it doesn't have to be completely square.
For game textures you'll want to use these sizes
128 x 128
256 x 256
512 x 512
1024 x 1024
2048 x 2048
4096 x 4096
These sizes can also be used in any kind of combination with eachother without issue, for example 1024 x 256.
As for the model, no normals are flipped, the model is not see through, the problem here is the axis of Y when exported. In your exporter make sure Y is set as the up axis, this should be default in maya.
Before doing this you'll also want to freeze your transformations and delete the history, I also suggest that you combine all textures into one texture map to save on drawcalls ( it's good for preformance ) unless of course the screen will be interactive, in that case keep that one separate.
http://postimg.org/image/p4kqh6kif/full/
Also, looking at this picture I noticed your viewportcube, the model IS upside down in maya. You might want to flip it the right way around before exporting?
Also I suggest you give names to all your submeshes in maya, as it is easier to indentify them in the editor that way and do troubleshooting, for example I would name them
Mesh_Computer
Mesh_Keyboard
Mesh_Screen