You can combine Mechatron with MYZ and you can combine Genlab Alpha with MYZ and you can combine them all. The specific campaigns in Genlab Alpha and Mechatron can be enhanced with the help with other the other books. MYZ is the "base" game so to speak and it's campaign can be played with animal mutants and robots 100% (and later on, the humans).
Is Mechatron compatible with Mutant year 0?
Mechatron has its own campaign. After that campaign is over, the robots for one reason or the other (depends on how the campaign ends) end up in the Zone and there the robots acts as a new class if you wan't to play MYZ. There is a chapter in the Mechatron book on how to deal with robots if using them with MYZ.
Could I use parts of it as a new/other sector or Ark?
Are the extra "sectors" PDfs for backers available for non backers? Are those sectors format the same as previously or a little more detailed?
All the special sectors will end up in so called Zone Compendiums eventually. All special sectors are have the same format, although some are larger than others.
Is it possible to play Mechatron as humans? or augmented humans?
No. The Mechatron campaign is all about robots that becomes aware and what they do when that happens. Biomechatronics (i.e. cybernetics, sort of) will be part of the next "class" expansion for MYZ (it will be called Mutant: Elysium) and will have non-mutated humans as the "playable class".
As I don't have much time to prepare sessions and adventures can I find somewhere a few adventures or detailed seeds of adventures on the web?
The game almost plays itself, especially the base game (MYZ). You don't need to prepare that much or at all. If you play the Mechatron campaign, you will of course need to read through the specific scene that the players will play, but other than that no. But as in all RPGs, you can of course expand the campaign and that will of course take preparations.