How can you use the same parts of simple/advanced XML in several views, without having to duplicate the code? Is it possible to create a parent view for all your views (or anything similar with/ without inheritance)?
Basically I need to have this big portion of xml inside all my views, and I do not want to duplicate it every time for obvious reason (code maintainability, efficiency etc...).
Unfortunately not, there is not really that kind of modularity in Advanced XML (short of creating custom modules and including all the logic in there -- that would not be modularizing the XML, it would simply be used in the XML). I would not hold out too much hope for such changes in Advanced XML in the future. You would be more likely to see enhancements to the Simple XML to bring it closer to functional parity.