2. There is no Harmatton. That was the code name for Maemo 6 (see point #1 above). There is no MeeGo/Harmatton for the same reason.
3. There are two builds of MeeGo. An Intel-based build and an ARM-based build. They are the same with regards to functionality. The only difference is the hardware layer (similar to Intel and ARM builds of desktop operation systems).