Switching from multiple thermostats to a single one
It sounds like you have baseboard heaters or similar. Since there is a heat source in each room, it doesn't make sense to control them all together (eg, every room on, or every room off) and since you also want a thermometer in every room, I assume that means you still want individual rooms on/off as needed. You just want to be able to set the whole house to some temperature, and not have to run around to every room to do so.

I am going to guess the motivation for this is that you turn the heat down at night or while you're gone for the day to save energy. I'd suggest the best way to do this is to replace all your therostats with programmable themostats. You still have to program them individually, but you only have to do it once. I have a forced-air system in my house with one thermostat, but it's programmed that I essentially never have to touch it, except for on holidays where I'm home during weekdays. A quick internet search shows it's very easy to find multi-packs of programmable baseboard thermostats for a decent price. 



You'd actually have a lot of flexibility with this setup. For example, if you only use a bedroom or two and the living room after 10pm, you could have the heat in other rooms turn off earlier. 



For fancier setup, you could use something like the NEST thermostat or a wifi-enabled thermostat (eg, Radio-Thermostat CT300 or Filtrete model). I have the CT300 at home, and the website and iOS app allow multiple thermostats to be connected: in addition to being programmable (and thus not generally needing to touch it), you could obtain your centralized control of all of them, albeit at a higher cost than simple programmable ones.