Hello everyone!

I'm trying to make Semantic MediaWiki extension and observing the documentation. I checked the Programmer Guide [1] and found that only the Doxygen documentation is currently available. Here are some questions:

1)  Are there any very small example extensions available,  whether or not some tutorials exist?
2) What are the main entry points to the code? For example, how can I add a numeric property Age with value 27 to the page User:Paul? Should I use SMWDataValueFactory? Or another example: what classes are to be used when I want to make an #ask query in my PHP code?
3) What classes are interfaces for extension developers and what classes belongs to the SMW core and should not be used by us? 

Hopefully after figuring out the answers to these questions I will able to improve the current documentation and it will make the life of other newbie extension developers easier. 
[1] http://semantic-mediawiki.org/wiki/Programmer's_guide_to_SMW

Sincerely yours,

Yury V. Katkov
Laboratory of intelligent systems
of the Saint-Petersburg National University of Information Technologies, Mechanics and Optics, Russia