YMMV but half my family has the 'tism- the men/boys tend to get diagnosed young and the women/girls only get diagnosed during childhood if they're nonverbal.
1. Less likely to have the telltale verbal delays, aggressiveness, and obvious stimming. These were pretty much the only thing considered "autistic" for a long time, too. On the flip side, I think being an autistic savant is also less common in females. Basically, the social idea of what autism even "is", is a typically male presentation. Heart attacks have the same problem, to be fair.
Women who aren't nonverbal are also heavily socially pressured to mask. Female autists do have the same obsessive interests, people are just much more willing to tell a girl to shut the fuck up. There's also significant social pressure to be "friendly" with the general glob of women you end up with as a social pecking order, but don't confuse that with being actual friends, it's a veneer of fawning to avoid being bullied. I think adolescent girls are just prone to extremely intense interests in general, though, cannot tell you how many lunch periods I endured listening to the same argument about who was going to grow up and marry which boy band member.
2. Autists mature slower than neurotypical people, but people usually expect women to mature faster than men. Guys get longer. If he has a good job, a dude can still otherwise live the same life at 35 he did at 18 without too much social stigma. Women get shit about when they're going to grow up and make babies.
My sister is a nonverbal adult and we fortunately have a fairly well-off family, I think her life would be pretty horrific otherwise. My brother was nonverbal until he was 6 and now he's a developer that lives in my parents' basement, so, a regular programmer.
3. I don't have any idea what it'd be like to be neurotypical and I don't see a lot of point in seething over it. You get the meat shell you get, in a lot of ways, and there's no sense being pissy about the parts you don't control. My attitude is probably because I'm old, though, I very much resented it when I was younger.
4. It's a trend. It'll pass.
5. Late 20's. I have a normal life and jerb and hardly anyone knows, though.