Yes it's ok to generalize. That is how humans quickly cope with an overwhelming amount of information. But you always need to be flexible and willing to recognize that not everyone fits the generalization.
This question can probably be interpreted a dozen different ways, so you’ll likely get answers to questions you hadn’t intended 
Generalization is a mental shortcut that simplifies things at the cost of accuracy. Ex: Dogs are canines. A Chihuahua is a canine. A wolf is a canine. But a Chihuahua is very different from a wolf.
I'd say it's sometimes ok, sometimes necessary for brevity, and sometimes accurate. Accurate = "All people need oxygen, water, and calories to survive." Brevity = "Generally speaking, people enjoy good food and good company so those situations work well for forming relationships."
Consequences of generalizations have a lot to do with how tolerable they are. If I say, "most people like pizza" there's not much harm if several million people don't. If I say, "all or most people of this gender/ethnicity/religion/whatever have X problem" that's a lot more problematic because it can easily lead to a consequence of harmful prejudice. When it comes to matters of ethics, beliefs, accusations etc. it becomes very important to handle cases individually as much as humanly possible.
You do it every day whether you choose to or not, because that's how the human brain works. So yes. Just be willing to change your ideas when a generalisation is no longer useful.
No, it’s never okay to generalize. Unless you’re saying my previous sentence in which case it’s okay.
I disagree. It's fine to generalize about all people all the time. Every single one of them loves it.
logistics? ... generalized population requirements.. ie. 50% are children, who need less of x.
Who cares if it's okay, that's subjective. I have limited clock cycles, attention span, and I have to prioritize what I'm going to expend energy on. I don't have time to get to know every person I encounter. I've got people and things in my life that matter to me, if I see you and you've got face tattoos I'm judging, cry about it. If I have a reason to get to know you maybe I'll be pleasantly surprised. I doubt it. I've got a life to live, pattern recognition is a core part of my nature as a creature that I'm evolved to have, I'm gonna make use of that strength. Maybe if you don't want to be judged as a scumbag don't deliberately express mutable scumbag traits. Even if I'm wrong about someone I won't regret it, it's highly unlikely that if I were more open minded that their presence would've enriched my life and they would've become my best friend. It's a cost benefit analysis. the likelihood that someone who deliberately expresses scumbag behavior wouldn't behave like a scumbag is below 50%, and where I am wrong, they don't need me to love them, they have people in their lives that know them and love them and why would they want to hang around a judgmental asshole anyway? Nobody really loses anything.
yes. but to so as not cause miscommunication problems, maybe keep it to close people who are in the know of what you mean.
Not if it causes anyone to treat people as anything besides the individuals they are.
There are many defenses for generalizations but they're all based on ethical laziness. For example, there is a growing number of people who dislike people from Russia due to them being in the news, something I probably don't help. It would be one thing to speculate to oneself, to wonder if Russia is the Florida of the Asian world for a reason, or that maybe their ethnicity lost the lottery when it comes to mentality, but to put this into practice on a general level and exhibit scorn to people "just because" they're Russian is wrong. It is unfair to anyone affected by a general opinion that they're treated based on association if they go against the grain, and being a good person just stops being incentivized. It's the mindset that gives us Hatfields and McCoys, or, in Russia's case, chronic crime families because Russia itself often punishes whole families for the crimes of a few family members, which I'm sure has no bearing on the sudden power of the Russian mafia, wink wink. Nations, spiritual groups, genetic groups, fandoms, you name it, people always think it's good to generalize them and it helps nobody. It's simply a form of assumption.
If I walk into a train station and there's a person in a red ball cap openly carrying a firearm I'm going to be extremely comfortable with my decision (as a man wearing a skirt) to sit far fucking away from them. They might be an absolute darling of a human being but generalizations are quite useful for assessing risks since we can't know everyone.
We should be extremely careful in the generalizations we make but generalizations are a useful tool for our safety.
I wouldn't discourage you, though perhaps this is because that's not exactly the same thing. Like I said, generalizations aren't bad to keep in mind. The seat you choose on a train is your discretion, and a stranger with features indicative of someone who might give you a hard time is a fair thing to gamble against. But you wouldn't be generalizing them themselves. I too am LGBTQ+ (via asexuality) and would jump at the opportunity to avoid many seeming incels or radical feminists (to use two examples, and not judging radical feminists themselves, many just clash with the sphere of asexuality) if I were choosing something like workmates, but I wouldn't do anything to verbally single them out based on things about those individuals I have not confirmed, such as making inclusion harder for them. In fact, if I had to choose either "innocence" or "guilt" as an emergency default, I'd choose innocence.