F900EX
Don't buy without joining the active and excellent PA46 pilots' association first.
http://mmopa.com/
Everything you need to know is there. And some. I fly a PA46 and the MMOPA is an invaluable resource.
On the G, you
do need a type rating, but not the HPA to fly the PA46 piston. You need a type rating
and the HPA if you jump straight to the turbine, unless you already have the atpl theory, in which case you don't need to sit the HPA. Alternatively, once qualified and experienced on the piston you can 'upgrade' with differences training and an examiner's flight sign off to the turbine without having to sit the HPA. Complicated, I know... Bottom line: you need a type rating regardless of engine varant, and to renew it with an examiner annually. And you might need the HPA too.
On the N, insurers call the shots. You need up-front conversion training - usually a minimum of 25 hours dual, or more depending on experience. And insurers insist you complete an annual training refresher with an approved instructor. So although different from the G regime on paper, it's similar in practice from a training point of view.
You do not need an IR to fly a PA46.
Engines - yes, there were problems in the early days. But engineering improvements, coupled with far better pilot education (thanks to the instructional and qualification rigours described above - training which was not required by either the FAA or CAA when the type was first introduced 25 years or so ago), has cured most of that.