There are many tutorials that capture everything you need to get flawless bakes. Understand how a lowpoly works, what transers well into a normal map and check the few clicks you need to know in, for example, xNormal.
Which modeling software do you use? Maya, Max? Try flipping your green channel. When Xnormal bakes a normal map the Y axis needs to be flipped (for example if you use 3dsmax).
You might try layering in some fog sheets to give the scene some depth cues. It would really separate the wall from the house, for example, and the house from the foreground and make the scene look deeper.
I was looking up some unity how-to type stuff a while back and found this: http://unity3d.com/support/resources/example-projects/charactercustomization Might give you some ideas on all the setup in unity.
Looking good ! Just a tip though about the face presentation, the camera focal is not really adapted for face close-ups, it deforms the face quite too much. Here's a little example to illustrate my point.
this is a quick random example. I made the center mesh x-ray to see the intersection a bit better goal is to get one connected mesh where you just have to clean up here and there a bit.
Depends on the renderer, and the version of Max. Usually you need a specific material type for that particular renderer. For example https://docs.chaosgroup.com/display/VRAY3MAX/Light+Emitting+Material+|+VRayLightMtl https://support.solidangle.com/display/A5AF3DSUG/Emission
What kind of engineering were you doing and does it relate to the kind of video game art you want to work on? For example, if you are modelling cars for a racing game, being an experienced mechanic is a huge plus.
This is great! I'd love to see it shown off with some nice lighting though, instead of just the plain old headlamp you have right now. For example, some lighting more like this would be neat:
Can of compressed air and a fine brush (get it in a camera store) I wouldn't disassemble it though. If there's too much dust, think of putting your PC somewhere else. Maybe on the desk and not directly on a carpet, for example.