Split the search engine and the web crawler
 

I would like the make the web crawling locally (altering /etc/hosts), and upload only the search engine on the web site (with the up-to-date phpdig tables, of course). This would ensure more security (maybe) and easiness (to me).

Is this already possible?

Yes, this is possible. You might have to edit the domain name in the sites table, and if you use CONTENT_TEXT, you'll of course need to FTP the TXT files.