If Sam is a recovering alcoholic, how can he work in a bar without serious risk of falling off the wagon? This alcoholic Troper was 2 years sober before she could walk down the wine aisle in the grocery without getting weepy and doubts she would ever be safe working behind a bar.
He bought the bar while he was still wealthy and a drunk. He owns the bar because a) he has no other income, and b) it's a constant reminder of just how far he's come.
I have indeed met a bar owner/operator who was a recovering alcoholic.
Without wishing to diminish the OP's struggles or difficulties, different people struggle in different ways, and they find different ways of coping with their struggles. Some recovering alcoholics, like the OP, find it difficult if not impossible to be near alcohol or the temptation it provides; others find it easier. Given his occupation, Sam is presumably one of the latter.
Also, being in the bar allows him to be surrounded by friends who would help keep him on the wagon.
What happened to Lillian Huxley, the English waitress Sam hired to replace Diane in the 3rd season episode "The Bartender's Tale"? She isn't seen or mentioned in the next three episodes, and after that Diane returns to her old job, which apparently was vacant. Where did Lillian go?
suppose it had to do with the Unresolved Sexual Tension.
The staff of Cheers apparently consists of only four people: two bartenders (including Sam, the owner) and two waitresses. Yet in many episodes one or two of these people just leave the bar in the middle of their shift for a long time, sometimes for the rest of the day, and the remaining staff doesn't seem to have any problems running the bar. Why did Sam hire three other people to work there in the first place, since clearly they aren't all needed? Or why not have the two waitresses and the two bartenders work in alternate shifts?
Convenience. The bar doesn't really need more than two or three members of staff at any one time, but having more staff than he needs allows Sam the flexibility to come and go as he pleases - which could be important if he spots a hot girl he likes. He extends the same benefit to his employees.
On the contrary, the bar opens at 10 and closes at 2 AM — that's 16 hours a day, 6-7 days a week. Even if the bar is only fully staffed during peak hours, it's hard to imagine 4 employees being enough.
Most of those sixteen hours and those six-seven days, however, the place isn't going to be that busy, and in any case, based on my hazy memories of watching it the place for the most part seemed like one of those quiet little places that has busy patches from time to time but otherwise mostly gets by from a relative handful of regulars. In reality, of course, it's so that they wouldn't have create redundant characters or pay more money to cast a lot of recurring actors or extras to portray characters who weren't necessary for the story just to fill up the bar-staff.
If Diane is a genius with several degrees, why hasn't she any options but being a waitress without a lover's patronage from her uni?
Diane does sort of seem like she'd be hard to employ as her self-centeredness cuts into people skills, and she starts off the series still in college (working toward a degree doesn't do much for a resume- trust me). Also, if I recall correctly, she started the series having never worked before and it is really hard to get a job with no experience. As for after she graduated.... I'm sure she probably just wanted to keep working so she could stay close to Sam, which is why he kept employing her (though they likely had some excuses for it).
She may also have gone back to school. At one point she says she's very close to getting a master's degree, then adds that she's close to a whole number of master's degrees. The implication at least in the first few seasons is that she keeps changing to different degrees, never completing them. So part of the problem seems to be that she can't settle on what she wants to pursue, which would continue on a personal level even after completing a degree.
Even if it wasn't abundantly clear that Diane, while Book Smart, isn't nearly as clever as she likes people to believe she is, being a genius ≠ being employable. Diane might be clever, but she's also quite flaky, neurotic, a bit unreliable and possesses a personality that rubs many people up the wrong way (pretentious, smug, condescending, a know-it-all, etc). It's not entirely surprising why potential employers might not consider her a particular catch for their organisation.
Why doesn't Robin seem to show any interest in being alone with Rebecca? It comes across as a very needy, one-sided relationship, yet he is spending lots of money on her in gifts and dates. Ignoring the fact that he's a real jerk, it seems odd that Robin doesn't seem to want to sleep with his own girlfriend that he's been dating for such a long time.
Robin is arm candy. She's too crazy to sleep with.
He was only dating Rebecca to get her computer password to spy on the company she worked for.
Why couldn't Diane write while being married?
It wasn't that she couldn't, per se—so much as she (supposedly) wouldn't. Sumner acts as if it's impossible—but his reasoning is that Diane would be far too occupied with her relationship with Sam to do something as major as "write the Great American Novel" in her spare time. While on its face a rather absurd notion...the fact that Diane herself admitted she hasn't continued on her book since she first came to Cheers seems to give at least some credibility to Sumner's argument—at least, enough so that Sam's vision of his future with Diane has her as never having finished the book.
Why is Carla the only waitress at the bar when the corporation owns it? When Diane leaves for Europe in Season 3, Carla is pressuring Sam to find a replacement, so she won't have to deal with the increased work load. And yet, Season 6 on, suddenly the issue is basically shrugged off and never really dealt with.