Hello, Ramesh !
Thanks for the answer!
> 1. <SearchIndex> is the lucene based index property tag, the binary
> tree structure of the repository nodes and properties, if I am not
> wrong.FYI: It excludes jcr:data.
>
This basically means that 'binary' data is not indexed, right? What 
about numbers?
> 3. you can run SQL or XPATH based queries.
>
Even without having the index?
> 4. The Search Index folder should be File system in the Jackrabbit 1.0
> release. However you can get latest and build the binary for the
> database based search index;I hope it is available in the source
> control now.
At least I now know that there is some activity in this direction! Cool!
Thanks!

Michael.