How do I make titles look like they are in the room as an object?
The technique you are looking for is called "motion tracking".  Currently, FCPX doesn't have the ability to do this on its own, but you could use Apple Motion or Adobe After Effects to accomplish what you're after.  Motion tracking, in general, follows patterns of pixels as they move around the scene.  Depending on the effect you're after, and the demands of your scene, you may be able to get away with just using this x-y coordinate data.  If, for instance, you wanted to replace the text on a moving truck, you could just track the corners of the truck and "corner-pin" the new text over top of it.

For more advanced projects, you need to actually reconstruct the camera's position in space.  This technique is called "3D camera tracking".  It's possible in After Effects (I don't remember if Motion has it though), and there are other apps which are purpose-built for this task, including: Boujou, Syntheyes and PFtrack.  Cinema 4D and Nuke also have this capability, but they do other stuff too.

However, 3D Motion tracking on its own is not enough to make your titles appear to actually be in the room.  You'll also need to composite the titles well, if you're going for trompe-l'œil realism.  And if you want any of the objects in the room to pass in front of the text, to give the scene more depth and realism, you'll also need to research a technique called "rotoscoping".