The questions you've asked are very complex and would require a book (more likely several books) to address properly, not a few paragraphs in this forum.
What further complicates it is that you may change to a smaller room in the future but you're not sure when and you have no idea what size the other room will be.
A speaker with strong and extended bass performance might work well in your present room but may totally overwhelm a smaller room and sound terribly unbalanced.
If I were in your shoes, I'd concentrate on getting good sound in my present room and if I had to sell the speakers in the future to get good sound in a different room then that's what I would do.
How many drivers a speaker has is probably not that relevant to your particular situation. Anything from a single-driver speaker to a multi-driver line array could work well in your room... depending on your listening biases, associated gear, aspects of room acoustics, etc.
In other words your questions are far too vague to be answered with any certainty. Perhaps others could suggest some informational links for you. My view is that there's no substitute for a little trial and error. At least that way, your preferences will be based on your own experience and not somebody's opinion which may or may not represent your needs.
And besides... rooms are almost like fingerprints... each one has its own acoustic wrinkles.
Maybe you should simply buy decent but robust monitor speakers (or any decent speakers) that don't have significant output below 80Hz. Then you could fill in with a subwoofer or two and only change the subwoofer(s) if necessary, when you move.
To be more specific would be like a blind man trying to discribe a scene he's never seen.
What further complicates it is that you may change to a smaller room in the future but you're not sure when and you have no idea what size the other room will be.
A speaker with strong and extended bass performance might work well in your present room but may totally overwhelm a smaller room and sound terribly unbalanced.
If I were in your shoes, I'd concentrate on getting good sound in my present room and if I had to sell the speakers in the future to get good sound in a different room then that's what I would do.
How many drivers a speaker has is probably not that relevant to your particular situation. Anything from a single-driver speaker to a multi-driver line array could work well in your room... depending on your listening biases, associated gear, aspects of room acoustics, etc.
In other words your questions are far too vague to be answered with any certainty. Perhaps others could suggest some informational links for you. My view is that there's no substitute for a little trial and error. At least that way, your preferences will be based on your own experience and not somebody's opinion which may or may not represent your needs.
And besides... rooms are almost like fingerprints... each one has its own acoustic wrinkles.
Maybe you should simply buy decent but robust monitor speakers (or any decent speakers) that don't have significant output below 80Hz. Then you could fill in with a subwoofer or two and only change the subwoofer(s) if necessary, when you move.
To be more specific would be like a blind man trying to discribe a scene he's never seen.