There are several national leagues; APA, TAP, VNEA, BCA and ACS, and each is a bit different. VNEA is only available to rooms that lease Valley tables, so this one is not available to many rooms. In most cities the players have a choice and the leagues will over time become what the players make it. Some of them are very social and others are serious.
The money the host location makes from league play is in what the players spend on food, drink, etc. while they are there for league play. So from that prospective, APA and TAP usually have BCA beat because the APA and TAP leagues are more "social" where consuming alcoholic beverages sometimes comes way before shooting serious pool. As far as money from the leagues, I don't think any of them pay out directly to the host locations for hosting teams. Many rooms pay all or a portion of the league dues or playing fees for the players to attract teams, so the return for them just to have the players there for several hours on league night is worth it.
In house leagues are whatever the room makes them. You have the same players there week after week in whatever numbers you are able to recruit and you can play your own format. Many players like to play league, but don't like having to drive somewhere different half of the weeks in a session, especially if they live close and drink a lot. On the other hand, with an in house league you can't offer regional and national tournaments for the players unless you have it sanctioned by a national league like BCA or ACS or get the APA or TAP league operator to make your in house league a division of their league. Many league operators offer in house divisions for pool rooms; maybe this is what you need to look into.
When you say cheating teams, are you talking about skill levels and handicapping? Any league that's handicapped will have sandbagging; count on it. APA and TAP are handicapped. Many BCA and ACS leagues and in house leagues are not handicapped, so this eliminates that type of cheating anyway.
It's not unusual at all for one location to have teams from different leagues on the same night playing side by side. Doesn't usually cause problems if there are enough tables and seating area and servers to serve everyone.
Good luck.
