Well, I have also looked at buying a room myself. Same questions as you have. However in looking at the responses it is clear that people think of pool in different terms.
First there is the business of pool/billiard rooms, then there is the sport of pool, and then there is the game.
They are all different, and depending on what you want from your business. You have to make a business plan that will attain your goal.
If you are interested in the "business" of pool, you need to attract people for its entertainment value. Music, food, beer and promotional ideas. One place where I play, gives every woman/female 2 hours of free pool on Monday evenings. Of course the place fills with young ladies, and of course the guys follow. They buy food and drinks and play all evening. Can't get a table from 9:00 pm until about 2:00, place kicks ass. Just an example of the "business of pool"
The sport of pool is promoted with tournaments, league play and lessons. The previous posters have addressed these ideas. This same room has lessons in the morning for a local high school. Exposure of the "sport" of pool is what the IPT is all about. I believe that every larger pool room should employ, or sponser, a pro player or at least a former pro. Just like the golf courses. Help the young players elevate their game to a competative level without being forced to "pay their dues" like some of us older players have. This will infuse the sport with players that come from a different perspective than the traditional.
The "game" of pool. Like every other sport when people play regularly, or come from out of town, there will be gambling. A separate area, with seating for tournaments and some money games provides interest and stimulates people to play, or at least work on their game. People that want to gamble will gamble. Try to keep it clean, isolated and drug free.
Loving the game isn't enough, you have to have a smart business plan that incorporates communication with the local community on their concerns, law enforcement, noise, traffic etc. and takes into consideration the demography of the area.