Quote - I've not experimented much with multi-figure groups, and am not sure how to create pose files spanning multiple figures.

It's not possible to apply a pose to multiple figures at once. By "pose" I mean a Poser script pose, as in a pz2 file, it may be possible to pose multiple figures via a python script.

A pose applies to one figure only, plus any prop, light, or camera parented to it, but not to another figure parented to it.

You could parent the base part of the chair to the BODY of the figure. That way any pose you save for the figure will include a pose for the chair. That's fine as long as you don't need to translate or rotate the figure's BODY actor. The downside is that if you move the figure's BODY the chair will move with it, so you could only translate of rotate the figure via its hip. Parenting the chair to the BODY should be a viable solution in most situations, so long as you are mindful of the restrictions on moving the BODY.

Apart from the above, the solutions get more complicated. A Python script might be able to pose multiple figures, or a combination of unparented props and figures at the same time. You could try asking in the Poser Python Forum, if such a script exists or could be made.

An even more drastic solution might be to edit the figure's cr2 so that it contained an extra actor in the hierarchy above the BODY. The chair could be partented to that new actor, leaving the BODY actor free to move without affecting the chair.

Quote - Would it just be simpler to animate the figure and chair outside of their intended environment, and save them as scenes?  Then could the scenes of the figure and chair be imported into the scene containing just the room?

That should work, but I recommend deleting all lights from the scene you intend to import, before you save it. I find that importing a scene that contains lights can cause conflicts with lights already in the scene you are importing into.