Qus on validator framework

Hi,
I am using Validator framework for the first time. I have some usual validations like required etc for which I have used client as well as server side validations. I have used server side validations just to ensure that when Javascript is disabled, the input should still get validated. However, isnt this an overhead? I mean when javascript is enabled, it will not let bad input reach the server but server-side validation will happen nevertheless. Can I in some way activate server-side validations only in case of javascript being disabled?

Also, there are some client side validations for which I need additional custom functions. Can I include my javascript file in some way so that it can be available to the javascript functions in the validator-rules.xml file?

Thanks