Few questions about searching using server side processing

Hi,

I'm using datatable with server side processing. It's working great and I'm polishing the configuration.

I have few questions left,

the search input :
- is it possible to configure his behaviour ? For example, is it possible to start requesting the server starting with 2 or 3 letters ?

- Is it possible to move the 'processing' div ? For example a loading gif in the center of the table ? As in my CSS, the processing appears at the same place as the input search.

And a last question; After datatable process my data's, I have to make some javascripts. It is working great almost all the time, I just put my javascript after the fnCallback function, as I'm overriding the fnServerData.

My problem is when I use the select input to choose the number of displayed elements. Let's say the default value is 10.
In my configuration, I load 50 elements and I'm using cache.

So datatable is displaying 10 elements and have 50 in cache. If I put the select to 25 elements, datatable is using my cached elements and regenerate the table, but my javascript is lost. Because datatable didn't call the server.
I'm not sure to be clear, but is it possible to call javascript after the 'select' entries has been changed ?

thanks !