As for impeachment, for impeachment to work the public has to be for it. Without the public approval it is bound to fail. Failure will give the Republicans another black eye like they got in their attempt to impeach President Clinton. In fact I think Obama would like nothing better than for the House to take up impeachment.
Let the president go ahead, let the chips fall where they may and see how the American people react. There are other ways to deal with executive over reach. Keep in mind, impeachment is overthrowing an election result. If it is attempted, you better be darn sure the president has done something real horrible to warrant it and the people realize he has done something so horrible they want him out of office.
Outside of that, take him to court, defund his initiatives, perhaps even a censure.