I definitely have other pursuits besides writing. Although I concentrate mostly on writing novels, I also draw, play guitar (not well, but still!), knit, bake, and sing. I also do yoga, travel, collect vinyl, and am a political junkie. Do these pursuits and interests help me become a better writer? In some cases, yes. I took guitar lessons mainly as research for one scene in a novel. Likewise with knitting. I didn't expect either to become new hobbies of mine, but it's nice. I guess they made my writing "better" in the sense that when I have a character play a guitar or knit (I don't want them all to be visual artists or writers, ha!), I'll at least know what the hell I'm talking about.
I guess that's kind of going off what said. Life experience is good research. Especially that awful date I went on the summer before, but that's a story for another day.
I tend to write whatever I feel like writing. Sometimes, I want to write historical fantasy stories. Sometimes it's science fiction. Sometimes it's realistic fiction. I don't write much poetry, but sometimes I do write some poetry.
It all depends on how I feel and if I want to put effort and time into my characters.
I've never tried writing a play or screenplay - at least, not since school - but I would never decide to limit myself to one genre or form. It's always good to try new things, and it's not going to hurt anything if you do it. I do worry sometimes about spreading myself over too many genres, but really it can't hurt.
Everything you learn in life can help make you a better writer, and you should never confine yourself to one genre. I started with sci-fi, but am now planning on trying horror, and have experimented with Second Person Perspective. If I had stuck to third person sci-fi, I wouldn't have improved nearly as much as I have. I believe there is a saying, "Variety is the spice of life" or something like that. If you don't have variety, then everything becomes monotone and repetitive, eventually.