Remote Action method runs in an.asynchronous mode.Hence accessing values from url parameter will get you null values.If you need any static values for your apex class to process use the parameters.pass from page to your apex method using parameter .
There is one way that i recently discovered to do this
Pass them in from the script on the page using {!$currentpage.parameters.something}
You still need to check for nulls in the code because it might legitimately be null