Everyone seemed to already comment things i've already said. But I'm still going to comment on stuff anyway. Though I don't know how well i can answer this, even though I'm Bi and Every story I write has wlw in it.
Like everyone else said, write them as people before writing about their sexuality. Design a character where being attracted to women isn't their whole character. Buuuuuuuuuut, as a half closeted Bi. I can honestly say that my sexuality Does have a part in my character. When I'm around people who I'm out too I talk alot more about pretty girls. ALOT. That might just be due to not being able to talk about it all the time though.
Also since it's a wlw LOVE story you won't have to worry about it. But for any story that doesn't focus on a relationship but has a lgbta+ charater. Say it IN the story. Don't go Dumbledore-ing it as saying so on twitter without backing it up in story, because that means nothing.
How does it work?
Gosh, like people said. Gender Roles go wild here. It's free reign, wild country! There is no asumption because someone is a boyfriend and someone is a girlfriend. I'm a perfect example since any "Het" relationship I'm in those lack of Gender Roles bleed into. These rules don't matter, anyone can send anyone flowers, and catch the spider, or pay for dinner.
There's also usually a lack of Toxic Masculinity (I say usually because yeah, it can still show up.) There would be alot more communication, alot more gushing compliments, ALOT less Ball n Chain type jokes, no belittleing because of gender or Gender based problems. ((This is why when people say write is like you would a straight couple. I find these relationships are way different))
My favorite example of a wlw is the video where a woman an her wife are discussing how ramen in cooked. The one asks "why am I in trouble?" The reply is
"you can't be in trouble, You're my wife"
It's short but feels exactly how it feels in a wlw relationship. This also answers the last question, you see them as the person you love. Thats it.
Oh also also, don't just rely on the concepts of butch and femme. Some people are One or the other, but alot of people can be a mixture of both, eithwr one oone day and the other the next, or just both at the same time!
what do you find attractive in another girl?
Oooh boy. It's a common joke between women and NB Bisexuals (and maybe men bi's too though i see it more common with the others) that with men there is a very small range that we are attracted to. (Note: this grows when i talk to them and get to no them). But with GIRLS!!!!! they are all so attractive!!?????!!. I can't even explain, steriotypical Men can say good body and good face (the worse man can say boobs and but). But like, no girl I've ever been attracted too it the same??? There have been some that I'm not attracted to but i still wouldn't know why???. I know I love smiles, if you're smile reaches you're eyes <3
This isn't really an answer but it also explains that there is alot less guideline to attractiveness with wlw.
I can't answer the trauma ones i have no experience or knowledge on that sorry.
I think last Advice is be careful... especially since you're straight. There are alot of Terms (like D*ke and Queer as examples) that are used commonly within the community. I personally use Queer alot because it's a good umbrella term. But these are also terms that have been are can still be Offensive from someone outside of the community. And while those extreme stereotypes of But lesbians you see on TV can exist and I've seen many wlw make fun of themselves for it. It can also be offensive from someone not in the community because that's not all that they are. (Don't rely too heavily on stereotypes, and alway check if one is teue or not?)
Last advice is check out content made by wlw. That will give you good examples.
additional note I totally forgot "where do you like to be touched".
With any woman I'm in a relationship with or want a relationship with and am close enough with. Being connected and touchy happens. Hand holding, face holding, not even doing anything just watching tv and we'd there have legs intertwined and arms wrapped around. is a constant touch there i don't experience as much when with a guy. The best is when they rest their hands on your hips. This can also change from character too character tho, since some people just don't like beinf touched