I find the requirements by searching for subsystems, as there seems to be no special block for requirements.
find_system(gcs,'LookUnderMasks','none','FollowLinks','off','BlockType','SubSystem','LinkStatus','none')
I get all the subsystems, including :
'test_simulinkmodel/SLVnV Internal Requirement Sub Block Name 1'
Is there some other way than to look for this (default?)string?
Also, when I know the path, is there some way to get the contents (Titles, descriptions?)
Which release are you using? In the latest release (R2013a), there is the System Requirements block. You can also generate (and customize) a requirements report, which should also work in earlier releases (I remember using it in R2011a for example).