If the intake manifold gasket is paper, what you can do is get it wet just before installing the manifold. Install it and start the car up. The heat from the block will dry the gasket to the surfaces and essentially seal everything up. Of course, this only works if you're ready to start the car up and the only thing you have to do is put the manifold on as you don't have all day to work with it.
As to the oil change, I'd drain it really good, put new oil in it, run it for a while, then drain, as you said. I'd only wonder exactly how long to run it, whether just until warm, or for 20 miles, or whatever...