Hi SandiMacD.
Welcome to our Mattress Forum. 
It is great that you’ve been having a conversation with Dewey. I know he’ll be able to answer the questions you have, but I will also do my best to try and point you in the direction of answers and resources and hopefully other Flobeds patrons will chime in with their experiences!
While we are able to evaluate an adequately durable mattress (which Saatva likely is not) it’s hard for us to decide or designate a best fit for you as only you know what you feel on a mattress, and what you prefer and need in terms of comfort and support. That said, the vZone is incredibly adaptable and, if for some reason you’re unable to configure the mattress to your particular needs, Flobeds will send you the Zone you need no charge for the first 100 days. No charge and nothing to send back. This really is a wonderful mattress.
It looks like their base is not split but I know Dewey would likely be able to suggest a compatible split base so that you and your husband can adjust your beds as needed.
Based on what I see in the image, this appears to be the case. I would confirm with Dewey, though, to be sure.
Unfortunately I can’t speak to the volume of the base as it adjusts, or about the split bedding, as I have no personal experience with this.
Great question! I hope someone with experience here will chime in. If not, you could ask Dewey to send you a picture of the remote.
To take some words directly from Phoenix… I usually recommend something in the “medium/medium-firm” range for a guest bedroom, as that will tend to work best for a wide variety of visitors. Hotels generally use the same philosophy, going with firmer mattresses and then more comfortable top-of-bed products to achieve a more medium comfort. Of course, since it is your mattress, you may wish to choose a comfort that is agreeable to you, as chances are you may end up using it more than your guests for naps, when one of you isn’t feeling well, etc. Staying with a more traditional innerspring design versus memory foam or latex is also usually a “safer” choice.
[quote]Does any company’s split matress go on any company’s split frame?
Or do I need to stick with the same company?[/quote]
Mixing and matching mattresses and bases is common. As long as the measurements are right and the weight of the mattress doesn’t exceed the max suggested weight for the base, you should be in the clear.
I hope this helps in some regard!
NikkiTMU