I think in the last arc when we meet another past Spirit Detective, she mentions she learned the spirit gun too. And I think when Botan taught Yusuke, she mentions it's sort of what most are taught. I don't think she'll have a very powerful one and without Genkai's teaching, I doubt it will be fatal by any means, but it will be useful to have in a bind that's for sure. And I think she already has some mild healing. I think when Kuwabara had his ass kicked by Rando, she mentions Kuwabara is too far gone for her healing to do anything for him. I do like the idea of Kurama having some greenhouse, maybe at school as you said. Maybe he's president of the club or something. And I do see Botan's reveal of having healing tied with plants, to be a cute one down the line.

I do think we will need them as we progress, or at least to be able to keep tabs on what the others are doing. I'm sure Yusuke is bored as hell back home, so he'd probably love to do more work for Koenma, but we can still assume Yusuke's school isn't too close to Kurama's so bringing him over to help, wouldn't be that, well helpful?

You really should go track down some episodes on youtube or the music, it's great to listen to when writing. I can make the intro if you want. It'll probably sum up why she's around and such. Just to double check:

This will be the second suicide in 2 weeks.

There is a demon who is undercover at the school, someone who Kurama supposedly killed many hundreds of years ago.

Some other weird, unexplained events have been happening around the school.

Kurama is in his last (?) year of high school at the academy.

It's the beginning of spring (?).

The service will be in the early afternoon at a smaller cemetery.

It's Monday and everyone has the day off.

The students attending won't be in uniform.