How to get querystring after URL mapping in web.config?

 Hi. All
There are two issues.
1. After URL mapping, I can't get the querystring anymore.
e.g. 
<add url="~/account.aspx" mappedUrl="~/someDir/myAccount.aspx?mode=edit"/>
If I try to add another queryString(e.g. id=100) to the end of account.aspx,
I can't get it from destination page(although I can still get "mode" querystring value).(a nasty workaround would be get the request.rawurl, and then go through the string value to get querystring)
Any ideas or clean code samples? 
2. If I add another querystring, the URL in browser address bar becomes  "~/account.aspx?id=100 ", which is exactly what I tried to avoid.. any suggestions ?  many thanks & ...