As writer of both, fanfic is easier to write because the world, character and rules has been established so you just need think about the storyline (As long you do a proper research). Meh, some fanfic writer even choose to follow close to canon event without making any major change, except...
No...
It's not easy either for me, so no.
Sometimes
Not sure, but maybe
I don't know what muse you are talking about
Maybe.
Well, lastly, happy writing too!
Varied, as I write heavily depends on the mood. I could always set the outline probably in an hour, but then filling in the detail and editing took me several hours to several days... because I got easily distracted.
Most of the time, I ended passed the deadline I set for myself (once a week)...
For me, it was because the story I write still have a clear direction and I also still having fun writing it.
If there is no both of them, it's really hard for me continue to write. At that point, I would take a break or even worse, put my story on hiatus.
I also write with the same purpose as you do-- (not for profit, just want to get the idea out of my head) and guess what? it was mocked by people so bad that I got even a threat on my DM's for it.-- (for ridiculous reason because I made it on trending with my bad writing skill lol.)...
I don't do that, because that's only make me feel sad, losing motivation and self doubt.
I know that I am not a good writer after all. I just want to have fun with my hobby.
You need a certain amount of readers to get those author titles.
Rising Author needs you to have at least 500 readers in total from all of your stories.
Well-Author needs you to have at least 1000 readers.
And if I am not wrong, Famous Author needs you to have at least 2000 readers.