Onedine

Da Eun
Yunhee

So far, there has been no mention of the third season, and probably the production of the drama ended at the end of December last year.

"Soon-Rok has similar tendencies to Yumi because both of their prime cells are love cells." https://tapcomics.com/tv/yumis-cells-who-will-eventually-marry-yumi/
In the drama Babi's prime cell is Love cell. I think so ? For now, it is his Love cell that makes the final decisions so far. Because in the webtoon it was Detecive cell, but so far we have not seen such his cell. Will it change? How did it was in the webtoon? I know that there should be a change in Yumi soon and her Writer cell will be her prime cell. But what about Babi? Was Detective cell always his prime cell in webtoon or not?

"The director of the TVING series “Yumi’s Cells” discussed season two of the drama, revealing what viewers can expect. He also discussed his filming experiences with the two main cast members, Kim Go-Eun and Park Jin-Young.
“The keywords of season 2 are ‘excitement‘ and ‘growth,'” said the director of “Yumi’s Cells 2.” “Yumi’s challenge of overcoming sadness from her previous relationship and moving on to a new phase of life begins,” he continues. “Babi approaches Yumi, who has a completely different charm than Woong. Yumi is excited by Babi’s honest and outspoken personality,” he added.
According to the director, if Yumi’s relationship with Woong was like a friendship, her relationship with Babi is like a romance between youths. “Rather than being conscious of others, it is a romance that includes the process of focusing on one’s feelings more honestly, making each other excited, and having a new dream,” he explained.
The director said of the lead actors’ chemistry, “The two actors communicated a lot with each other while filming on the spot.” “When I looked at the two actors closely monitoring each other’s actions and exchanging opinions in a low voice, I felt like I was looking at Yumi and Babi,” he added.
“Actor Park Jin-Young’s eyes were deep and attractive,” he went on to say. “When he looked at actress Kim Go-Eun, I felt he was in love with her,” he said. “There were many processes of filming with new stimulation through the opponent’s actions,” the director explained. “Those processes brought a much deeper flow in the relationship between the two characters.”
Finally, the director revealed what fans can look forward to most in “Yumi’s Cells 2.” “I think you might fall in love with Babi,” he said, adding, “The activities of Babi’s adorable cells are a bonus.” “The slightly different story from the original webtoon will bring new tension and fun,” he added."
https://tapcomics.com/tv/yumis-cells-2-director-talks-about-yumi-and-babis-romance/

we don't know

It's just that he thinks more about not offending others, about not hurting them, than about his own good. It's such a compulsion to be good, even at the expense of yourself. That is why many people find it difficult to understand him because they are more used to selfish peopl, to gain something at the expense of others, not to sacrifice for others. Which is also not good, because the self-sacrificing person runs the risk of being hurt. Even in the scene with Woong you could see that Babi felt sorry for him, and he was, in a way, his rival. But even to him, Babi wants to be nice. Something like this may makes his behavior seem insincere when it isn't. It just comes from his psychological compulsion to be nice. This may not be good for Babi's life, because his kindness may be perceived as something more significant and there may be misunderstandings.

At the recent press conference for “Yumi’s Cells 2,” Jinyoung described his character Yoo Babi as someone with “kind kid syndrome.” Jinyoung explained this, saying, “It’s an obsession. Babi has this compulsion to do well for others. To all women and even all men. If I’m to infer about a few of Babi’s actions, there are a lot of aspects that could be misunderstood. Although this doesn’t come out in the drama, if you look at Babi’s story in the original webtoon, he says, ‘I thought I just had to blindly be nice.’ That’s the point where I felt that Babi had ‘kind kid syndrome.'”
https://www.soompi.com/article/1533158wpp/got7s-jinyoung-describes-his-similarities-to-his-yumis-cells-2-character-how-peaceful-he-feels-with-his-members-and-more

"At the recent press conference for “Yumi’s Cells 2,” Jinyoung described his character Yoo Babi... "

In the webtoon, Babi's mother is dead.

As far as I know, Kim Go Eum said goodbye to Yumi after the shooting for Season 2, so I guess it won't be.

There are a few more scenes that those who read the webtoon picked up. The code number for Babi's apartment, 1224, is the same as the Soonrok code number in the webtoon. There was also a name associated with a reindeer on the elevator wall in Babi's house. The first time Yumi was in Babi's apartment, her T-shirt had the word "editor" on it.
More about Soonrok's scenes given to Babi here:
https://twitter.com/taerabyte_cj/status/1537811290483494915?s=20&t=_vB-AgVL8nbhsSKNrlbfFw

But he's not perfect. He doesn't like his father. He didn't tell Yumi about Woong's financial situation, but he wasn't sure what was driving him, and he felt remorse. Besides, his cells aren't perfect. Only his Love Cell is almost perfect. This cell wants the best for others, even if it hurts it. Babi just respects the decisions of others and is not willing to hurt them. I have the impression that he thinks more about others than about himself, so as not to offend them, even at the expense of himself. This can be considered a disadvantage.

Because the Mexican fiesta pary is commonly associated with joy, openness and happiness. Perhaps it was all about it.

The producer has the final word. If the drama or film are not independent, i.e. the director, the script writer does not provide funds, the script is what the producer wants it to be. I have no idea what producer Yumi's Cells 2 wants. When the season ends, we'll find out.

They can. It depends on the viewers. I think producers care about the money they get from drama the most. But if someone wants to watch the character development, I think Season 1 and Season 2 so far are doing quite a good thing in this regard.

Probably most people know that this character, Da Eun, will appear. But also many people know from the actress herself that she had very few scenes. Also, some people believe Jinyoung's words that Season 2 will leave fond memories. If the drama were to end up in a mess, a betrayal, or something like that, it would be hard to leave that impression. We'll see how it all turns out. Maybe the script will end it all nicely, that no matter how it is, most viewers will like the story.

The authors of the drama and the actors themselves say that it is not necessary to watch season 1. You can just choose to watch both seasons or just the 2nd season. I watched the 1st season and watching the 2nd season, but I can see that you can understand the drama without watching the 1st season.
I think not everyone is interested in character development, step by step. Some people just want to watch - sometimes funny, sometimes nice, sometimes touching, sometimes sad, sometimes sexy - an interesting story.

I forgot about it. At the start of Season 2, it was mentioned that Yumi is now 33 years old, so the wedding is just around the corner.

Drama was filming scenes with Yumi and Babi in Jeju and it looks like they have wedding rings (or rings as just a couple, which is the custom in Korea). But maybe it will only be Yumi's dream. One of the promotional material has this scene with rings.

Yes, but in a much more innocent way. They said so.