About your last question, let me add something to Federico's answer. Unless you are a lawyer, and I'm not one, in Italy it is frequently difficult to properly navigate and understand the constraints imposed by the law but, as far as I understand, both the RTD-A and RTD-B positions1 require a PhD or equivalent title2. These are the current entry points if you want to aim at a tenured position.
Probably the only position that in Italy does not require a PhD is the assegno di ricerca di tipo B (the tipo A, instead, is a post-doc position), which is the typical way used to hire someone who has finished the standard three-year PhD period but hasn't yet defended the title. But if you don't have a PhD, you cannot go beyond this, and this position cannot be turned into a permanent one. Without a PhD you're also quite at risk of not being selected if someone with a PhD applies too.
1See this answer and this one for a more detailed description of these positions.
2If you open a bando (the application rules), you will likely find that the first 1-2 pages just list the relevant laws, decrees and university regulations on which the bando is based, and it's a daunting task to trace back the origin of a certain constraint.