Android Runtime Layout Tutorial

You forgot to set your contentView. You should add

setContentView(layout);

At the end of the onCreate method

android : change layout screen in runtime

There are many ways you can achieve that.
1) you can use a ViewSwitcher. It uses two layouts and you can switch them back and forth.

Here is the tutorial on it.

2) you can override setContentView in the activity and implement your logic in it and call it from anywhere you want. Like you can set a boolean flag in it and set the layout accordingly! you don't need to restart the activity to do that.

Tab Layout tutorial incomplete?

Since they seem to update these tutorials occasionally, I wouldn't doubt they forgot to mention this part back when this question was asked. They appear to have added a mention to this requirement in the tutorial now (as of 12/20/2010) in step 2:

Duplicate this for each of the three activities, and add the corresponding tags to the Android Manifest file.

Unfortunately, since these are beginner tutorials, they should probably include what the XML tags should look like. Prior to this tutorial, they don't mention how to add activities to the manifest (though you add an activity at the end for hiding the title bar). The markup I used was identical to that on the other question mentioned in the OPs own answer:

<activity android:name=".ArtistsActivity"></activity>
<activity android:name=".AlbumsActivity"></activity>
<activity android:name=".SongsActivity"></activity>

There is a full reference on manifest activities on the Android developer site.

Android layouts: how to approach dynamic generated survey forms

You can create a template for each of the question types in xml and then just inflate that at runtime and fill in the correct information. This will allow you to redesign the look without having to touch code.

Repeat a layout at run time in android

here you can find my answer about creating and populating a layout list on runtime.

Android Runtime Layout Tutorial