Just so you know, the following information is based completely on what I've read online and logic. I've never actually built an RMH.
Logic would dictate, because rocket mass heaters do not blow hot air into other rooms, that you would need a source of heat in each "pod". (RMH ducts can be put under the floor to maximize space if you're not using a bell design). I'm sure there are more clever solutions, though, that would enable a single RMH to heat the whole area. Perhaps you could install radiant floor heat in all pods, connected to a single heater... But then again, I have never heard of anyone doing something like that for such a large area. And I lack the hands-on experience that would tell me exactly how far a heater could stretch.
As for a type of rocket mass heater, there's a lot of information online about such things. I'm going to build one myself (soon, hopefully) and I've learned a lot about them -- or, more accurately, I've learned as much as I could from the online resources I've so far found. There are two types of "feed" that I've so far encountered -- the regular ol' "J" kind and the easier-to-use (but more difficult to build) "Peterberg batch-box" kind. J tubes are smaller (can hold less wood) and need to be tended quite often. Batch boxes, in contrast, require much less tending for a steady fire (maybe twice or thrice a day) because there is enough space in the box to hold a lot of wood. However, they need to be constructed out of firebrick or heat-resistant concrete, and the air intake usually requires welding.
Do some research to learn about them. If you've already done research, do more.
Personally, when I finally build my own, I'm going to first try a "J" kind, to get a feel for building RMHs. Seeing as I'm not going to have my own house (and workshop) for a while yet, the "J" kind is a better option for me -- no masonry to cut, no welding to do, and no cement to cast. But the batch box looks much better for a house-heating option -- you won't have to feed it every 15-30 minutes.
There's another design decision to make: whether to use a bell design or a flue design (I think it's also referred to as "contraflow," but not entirely sure). There are lots of great posts about this already, and I can't pretend to know much about it (I'm just a seventeen-year-old sustainability nerd, after all, and not a mason), but here's a a site written by somebody who is: Article
And if that didn't make sense, I don't blame you, and here's another: Article
Basically, with a bell design, all the hot gases being put out by the rocket core go to the top of the "bell." As they release their heat through the skin of the bell, they sink to the bottom and are replaced with new hot gases. They exit through a hole at the bottom and possibly into another bell. This ensures that only the coolest gases will leave the system, allowing maximum efficiency. Besides, with a bell system, the gases are not as likely to "back up" into the house once the heater is warm. Here's an article listing bell RMH projects built by experienced masons, including commentary: Article
The site is a bit confusing, but you'll probably figure it out.
With a flue design, hot gases may or may not exit the chimney along with cooled ones. Therefore, it's not as efficient. However, it's unbeatably easy and cheap to build -- requiring no masonry skills and utilizing ductwork. This is the kind of RMH you probably picture when you think of the term.
Anyways, just throwing ideas and information out there. I hope the articles I've shared help at least a bit. If I have any incorrect or disputed information in this post, I'd appreciate being told -- there are varying opinions on how to build these things.
As for recommendations, it really depends on how willing you are to work hard. If you build a batch box rocket bell heater, you'll basically be building a masonry stove. It'll be really nice, but it'll be difficult. And if you have to build three of them -- well, let's just say that you don't want to have to do that. Besides, if you want to save space by putting it in the floor, your only option is to use a flue design and probably a J tube.
I wish you luck.