I'm to do a quick run through and ive my views on things...I play hockey, have for like 15 years and I'm 18...
1. Goalies really have no reason to be in fights, not to mention if they go into a fight with their gloves still on their blocker (glove with large flat surface) could be devastating. Not to say goalies haven't fought players before
...see Ray Emery (complete clown)
video of fight
Wiki, intersting stuff...
2. Yes they have a position for players who can fight at all levels of hockey...they call it the enforcer and they tend to be 3rd or 4th line players. You can go into camps for Junior hockey (ages 16-21, non Highschool) and just impress coaches with your fighting and make the team to do exactly that.
...see Tie Domi (mentioned already, legendary BA)
Domi Tribute video
3. Goalie Fights...like stated not that common but Here is a video with a couple...plus other goalie freakouts that was put together last week
...Cloutiers fight as mentioned is one of the best ever.
4. All Roy's are clowns. I've played against Jonathon (the one who beats down the goalie) he got pulled against us in the 2nd period. That whole series (QMJHL playoff series) was a mess, Jonathon was like their 3rd string goalie...
5. I will disagree with the fact that fighting is limited to the pro leagues. Any Junior hockey game you go to there is a damn good chance there will be a fight. In Junior hockey you typically aren't paid...although there are a few leagues where you are in Canada which you do get paid called Major-Junior (QMJHL, OHL, WHL) it is the main North American alternate to college for getting to the pro ranks.
*Note: once you get paid such as in Major-Junior hockey you cannot play college hockey (at least in the states)
The reason you don't see more of it at other levels is because of the harsh backlash...In ohio HS you get 2 games for fighting, and my school usually gave an additional. Some youth organizations like the one in Cincinnati are nazis and you than have to go infront of the organization board members to discuss the incident.
6. The NHL farm system is very similar to baseball's. There are many leagues in which future prospets and players close but not good enough to make it yet are at. As well as calling players up and demoting them are possible. Only difference is that not all players in those leagues are under contract with NHL team...only some. Althugh most have been drafted.
and again there is Junior hockey ages 16-21 where you either follow with a) college hockey b) Major Juniors c) stop playing super competitivly
Juniors in the states is tiered...Tier 1 is the USHL; almost all kids play college hockey. Tier 2 is the NAHL; majority kids move onto the USHL, or college hockey. Tier 3 is very entry level and an vary widely but is a good steping stone to other leagues and can rarely end up in D-1 hockey. Club hockey in college after (still competitive and good hockey) is very common.
Canada is similar but I'm still a little boggy on it...but I'm trying out there next year...so I'm going to learn soon enough...
7. And yes, there is a serious unspoken code to hockey.