Hey buddy, welcome to the US. First, I will give you a rundown of the types of basketball played in the US. Here are some of the general types: recreational (all ages, U8 to adult), competitive recreational (called AAU or travel basketball, ages U11 to U18), amatuer (high school, college), and professional (lower level pro leagues, D League, NBA).

We do not have "divisions" like you do in Italy, and the level where you can referee depends 1) how good you are and 2) how good assignors (people who assign referees to games) think you are. Do you happen to have video of one of your games? If you could post it or send it to me we could give you an idea of how your "fourth division" referee skills translate.

To answer your questions:

1. Yes, it is best to start with the state high school association. Find out how they license officials and get signed up. Then try to find out their process for assigning games. Do they assign by association? Join the local association. Do they use an assignor? Find out who the assignor is, call them, and explain your situation and reffing history. Ask if there is a way to see you work. Do the schools themselves assign the games? Find an experienced referee who can help you getting to know Athletic Directors and start calling schools.

2. Generally refs here start with youth basketball (recreational or competitive), progress to middle school games (7th/8th grade A/B teams, lower level high school games (C Team, Freshman team, Sophomore team, Junior Varsity, Varsity), and then to college games (NAIA, NCAA Division 3, 2, 1) if they are good enough. But it is not a linear progression because every referee grows at a different rate so there may be some college refs who go directly from middle school to college games, and other refs that may go from doing competitive youth games to doing high school games. I'd suggest you referee whatever type of game you can to start -- you can start being picky about what kind of basketball you work later.

3. Advancement to higher levels varies. Often it involves going to a "camp" where you referee games and are observed by more experienced referees to see how you do. If they like you and think you can referee, then they will hire/begin to use you. If they don't, listen to the comments they tell you, take what works for you, and work hard on improving your game. The best thing to help you improve (especially at the start) is to get video of your games and watch it carefully to see what you can improve.

4. Yes it is possible to officiate NCAA games in a few years, depending on whether you are good enough and the observers at camp like you.

5. For high school games you will typically stay in that state. If you live near a state border you may choose to join the other state's high school association to referee in that state as well. If you do higher level games like college or lower professional leagues you may travel out of state often to referee games.

6. Yes, referees are paid. The pay ranges anywhere from $20 for a youth game to $50-80 for a high school game, $150-250 for NCAA Division 3 and $1000-2500+ for NCAA Division 1.

7. We have three main rule sets in the United States: NFHS (National Federation of High Schools, or Fed for short), NCAA-Men's (National Collegiate Athletic Association), and NCAA-Women's. At the college level the rules between Men's and Women's games are different. Unfortunately, there is not much use of the FIBA rule set unless you are working scrimmages/games between the various US national teams and other countries national teams. There is also something called "IAABO" (International Association of Approved Basketball Officials) but I don't really know if that is it's own rule set or just modifications to the rules or mechanics or what. I'm sure someone else can chime in if Pennsylvania uses IAABO.

8. The key to being a good referee is minimizing your mistakes and being able to handle situations that come up in the game. This ranges from calling the plays, to knowing how to adjudicate the weird rules, to managing frustration on the part of players/coaches, keeping the game under control, and being a good partner and someone who other refs like to work with. Most of those things can be helped by having lots of experience, which sometimes means reffing a lot of games and sometimes means picking which games you work carefully. As you start out thought I would suggest giving any type of game a shot, at least until you get comfortable knowing how things work in your area. Good luck!