Since your query already seems to take into account the user, I think you can use the @user-id built-in field in the SSRS report to populate an internal parameter (let's call it "@DomainName"); you may need to trim that username to remove the domain portion, depending on what your dataset looks like.

Then you can pass that @DomainName to the query like you seem to be doing now just in the subscription. Make sure to set @DomainName first in the parm list so it's the first thing that populates when a user hits the report, and then you can filter the other parms and/or data automatically.

Hope that helps or at least points you in a direction. I'm not sure about the snapshot stuff but I think that's also possible.

Cheers,

Eric