Where is my blob stored?
I got something finally,

After further reading the DOC and making some test:


Yes, by default, depending on the size of the row, some blobs will be stored in row and other out of row.
Yes, following this you should be able to determinate it:


  LOB values are stored out-of-line when any of the following situations
  apply:
  
  
  If you explicitly specify DISABLE STORAGE IN ROW for the LOB storage    clause when you create the table.
  If the size of the LOB is greater than approximately 4000 bytes (4000    minus system control information), regardless of the LOB
  storage    properties for the column.
  If you update a LOB that is stored out-of-line and the resulting LOB    is less than approximately 4000 bytes, it is still stored out-of-line.
  
  
  LOB values are stored inline when any of the following conditions
  apply:
  
  
  When the size of the LOB stored in the given row is small,    approximately 4000 bytes or less, and you either explicitly specify ENABLE STORAGE IN ROW or the LOB storage clause when you create the table, or when you do not specify this parameter (which is the
  default).
  When the LOB value is NULL (regardless of the LOB storage properties    for the column).
  

No, this is just the default option, when the blob is too big(arpox 3800) it will be stored out of row