And what if a MTOW is over 5,700 kg ? Then do I need a type rating ?
If the aircraft has a type certificate then you'll need to have done a type course on the aircraft as well as have the necessary minimum hours of experience on type, certified by another type-rated LAME. The exceptions to the 5,700 kg MTOW rule is with aircraft like aerial ag aircraft, Air Tractors and the like, which are over 5,700 kg MTOW but are not type rated. As I said, best check with your country's airworthiness authority as to which aircraft are type rated and which aren't.
In Australia, I believe most people who own such aircraft have them maintained by a CASA Part 145 approved maintenance organisation.
Cheers,
John