important tax, legal questions for those seperated

[theotherhalf]

My H and I have been physically seperated since 8/07. He lives in a rental house in town and our girls and I live on our farm. Last year we filed taxes as if everything was still the same. We continue to share one bank account only. He writes the checks for his rent, utilities, bike payment, and his misc stuff. I write all the checks for the bills here and farm stuff, Nothing is seperated finacially or legally. H used his address when purchasing a bike so the bike pymt stuff goes there, and it was licensed in that county so now all vehicles in his name are registered in that county and have his address. Otherwise everything else says he lives here.

My questions are.
Those of you seperated at least a year, do you file taxes as M, or do you LBS file as head of house hold? Does your WS use his/her physical address or your address? Can we get into trouble with him using two addresses?

Any tips/warnings/ or advice???