In Europe, there is more of an institution of playing what billiard players call the "small games." These games are:
Straight Rail- where your cue ball needs only touch the other two balls. This game is alive and well in many parts of the world except the US, where there are still some areas where the game is played, including a league in New York.
Balk-line- As straight rail became too easy and boring to watch (because the best were never really missing much), lines were drawn on the table and players were only able to make a small number of straight points when all three balls were inside a box. After making the points allowed (one or two), you must drive a ball across a line. It can come back into the box. As long as a ball crosses a line it is ok.
One-cushion- Probably the best game to learn the basics of three cushion. The title says it all...you only need hit one cushion and both balls.
As far as the diamond system, while many players use systems, the top players are split (although more use them not). The game can be played by feel and is by some of the best players who have ever played the game. It depends what kind of person you are. If you are going to learn systems though, stick to the Ceulemans systems, because there are a ton of them that are not worth the time to read. Start in Ceulemans' book (if you can find a copy), it is the only one you will ever really need as far as systems go.
Bridges are short because a short bridge reduces the margin of error of stroke-related issues. Since we are commonly applying lots of english, there is little room for error. Also, billiard cues are stiffer and the shafts tend to get thick very quickly. The bridge loop would have to be pretty big to allow for a long bride.
On the pro level, all of the games I mentioned above are played but they are very limited. Three-cushion is widely played and recognized as the pinnacle billiard sport, although it is probably one of the easiest billiard games to learn to play well.
The best 3 cushion players can make a nice living, but not anything like the top snooker players. With endorsements and tournament earnings, also exhibition proceeds, there are several who can make $125,00+ annually. However, go outside those limited few and a player would be hard-pressed to make $60,000 annually, taking into consideration that from that income all of their expenses must be paid. Many countries subsidize their billiard federations. In South America, many countries will pay for their players to go to other countries as long as they have an official invitation to the tournament.
You would be doing well to play some billiards if you want to improve your banking and kicking skills. A few years ago when Kier Graff was writing about learning the game of pool for Billiards Digest, I gave Kier a lesson, which he wrote about. He was only an average pool player, and after about ten or twenty minutes, I had him kicking at balls like a mad man. I showed him some things that allowed him to be confident about kicking. Before the lesson he admitted that when he was kicking, he was basically just guessing. During the lesson, he began kicking to make the ball or to hit a certain side of the ball for safeties. I don't remember which issue it was in, but if someone knows, it might be worth reading.
Do carom players look down on pool players? Some do. But hey, at least snooker players look down on us all
Really, billiard players have a lot of respect for pool players. The main problem billiard players have with pool is its image of dirty rooms, hustling, back stabbing, etc. Billiards has all of that too, but without the dirty rooms