

Absolutely agreed on learning to write Kanji, as well. Especially given that even PARTIAL learning will teach you how to recognize the writing of characters you’re not familiar with, which is critically important for being able to look them up in a dictionary.
Do you need to be able to reproduce every single Kanji you know? No. Should you spend time on learning how to write them? Absolutely, I’d 100% recommend it.
One of the wonders of being an adult is that our peers stop being limited to people who are the same age as us. Now in my late twenties, I have friends 10 years younger than me, and 20 years older.
Dating is different than friendship. But it’s not so fundamentally different that I’d feel weird about dating an adult in those age brackets. Is it more likely I’m going to date someone closer to my age? Sure. On average, they’d be more likely to be in a point in their life that I’m looking for, but it’s not a guarantee.
I’m a bit above your age bracket in question, so I’ll comment on what advice I might give to a friend in that age bracket. Were a friend of mine to be thinking about getting involved with someone 20 years their senior, I’d tell her to think carefully. She should spend some time thinking about what she wants from a relationship. If she’s still interested in going out late and drinking, or she likes raves, I might say she should consider whether her potential partner is still looking to have those things in their life. The opposite too, if she’s the “comfy book and a movie at home” type of gal, is she wanting to be with this partner who’s super into going out adventure biking all the time. I’d tell her to think carefully about why she’s interested in this person, but also what this person sees in her.
On average, people gain some level of “maturity”/“wisdom”/life experience/je ne sais quoi about them as they get older. On average, people tend to date people who are similar to them in some ways. On average, partners will have similar levels of this vague term for aged distinction that I lack a term for. Relationships that don’t follow this pattern are, then, unusual. Not bad or wrong, necessarily. My left ear is substantially asymmetrical from my right. That’s unusual, but not a problem, except I have to be careful when finding earbuds that fit both ears properly. Similarly, those who date with large age gaps like this are unusual. Not inherently bad, but with some things to look for. It is more common that these sorts of relationships have some sort of unhealthy dynamic. Maybe that’s a predatory power dynamic, or financial inequality, or just some skeevy 40 year old who thinks “coeds are hot sex toys, especially when they have daddy issues”. Or, maybe they just both REALLY like boats. Like, they met when they both learned they were building a to-scale hand crafted replica of Viking longships, and it was a wonderful match for them. Or, maybe they both have a kink for plastering lizard scales on themselves, putting on goggles, sunning themselves on the patio, and then fucking like rabbits. The reasons they can find love for one another are many, and are not mine to limit, or to judge. I can judge them, mind you. If their relationship is based on how much they both love drowning puppies, they’re awful people. But that’s who they are, not who they love. That’s different.