1.Even if you use string formatting sometimes you still need whitespaces at the beginning or the end. On these cases neither escaping with \ nor xml:space attribute helpes. You must use xml encoding  for whitespaces.

2.I found a solution on this issue report : http://code.google.com/p/android-apktool/issues/detail?id=14

This is the same idea that Duessi suggests. Insert \u0020 directly in the XML for a blank you would like to preserve.

Example :

<string name="your_id">Score :\u0020</string>

The replacement is done at build time, therefore it will not affect the performance of your game.