I am a newbie author working on several project but I'll just use one to answer most of the question here 
https://tapas.io/series/The-Emperor-and-His-Thief
When I first started this, I was on my first year of university. The basic planning/research took me a year. The world-building itself took me a month. Then the research on how the imperial palace works took quite long. The Emperor's harem is the one that gave me a lot of headache that I gave up and simplified it. Of course, now that it is currently under editing, I decided to add things that I were not able to add before.
Back to the point. I only started publishing the story in wattpad after a year of planning/researching. As for how much... I can tell you that the amount of tabs I used for research for this story is more than the amount of tabs I used for my assignments! 
For this one, I can say that I have one project that is currently in the process of planning even after a year. The reason for this is because of the settings. It is about a quick transmigration that was inspired by other QT novel. Because each arc is a different world, I have to plan out each world separately while also making links to the story. Choosing which kind of world setting to use is already hard enough. I haven't started writing even the first arc so I only throw out the introduction of the MC/System duo 
Another one is this one:
https://tapas.io/series/To-Rise-Again-in-the-Apocalypse
I did not do much planning for this because it was set in a modern setting. The world building took less than a week, and the research for cultivation rank took around 2 weeks. After that, I began writing the first chapter which I separate into several episodes here in tapas. Wanted each episode to be a quick read so its only 500-800 in estimation.
As for how much time I spent on planning every day, I'd say only around 15minutes minimum (only because I have other projects to be done too)
Good question! Man proposes, god disposes. I can plan, and I can estimate. But the outcome is severely different from my expectation. For the first series that I linked, I thought it would be around 100-150k words (with 20k minimum for each arc/major event). It has five arc/major event. So it should take about a year and a half to finish. But I only managed to get to the third point of the story, and I have already graduated from university. The reason was... for 9 months, I couldn't write at all due to drumrolls broken pc! Luckily all my first drafts is handwritten so not much major damage done
But that is not all. My estimated word counts seems to be far off too. It is currently at 140k words, soon breaking 150k words. I did not plan for it to reach 100 chapters, but with the way it is going, it is reaching there (currently at chapter 86 in wattpad). Even if I remove the papapa scene, it will still be 100+ chapters