Not sure I can answer all of your questions but here is what im aware of.

1. Check out the Bootcamp demo project thats with unity and lookin the Hierarchy at Boundaries. They used a series of box colliiders (with no texture applied) to create an invisible wall that the player can not pass through. It sounds as if this would fix this issue.

2.I cant answer but I recommend searching the forums.

3.A couple of different methods but good links. Just search these forums. http://answers.unity3d.com/questions/7924/save-load-game-question http://answers.unity3d.com/questions/18942/saving-and-loading-help-please

4.Take a look here for alot of the GUI run downs through unity. Its not to bad considering 2 months ago i didnt know any of this and I get it. Its located here. http://unity3d.com/support/documentation/Components/GUI%20Scripting%20Guide.html

5.Refer to question 4 and follow through the link as it should cover menus as well.

Note, I have assumed a certain degree of programming experience on your part, as you say you are a C++/C/C# programmer.

1. Create an empty gameobject and add BoxColliders to it, moving them to where you want to block the player from going.

2. I don't think there are many such tutorials for various reasons, mostly cause the code needed depends entirely on how you write your game code. For instance, the definition of player differs greatly from game to game. Seeing as you have programmed before however, you might be satisfied with just looking through the script reference. More specifically the Input class and the transform.position property. EDIT: After re-reading your question I realized you just might not know where to write the code in the first place. When I was in your shoes I did the 3D platformer tutorial, and after that I didn't have to do any more Unity tutorials.

3. Just cause your managed code is running in an embedded version of mono, it doesn't mean you can't use the System.IO namespace.

4. On top of the link lowcrawl provided, you may check the GUI class in the script reference.

5. See 4.