Having 源泉徴収税 deducted from income as a freelancer – how does it affect my year end shinkoku?

I work as a freelancer full time for 2 places. Both of them pay me withholding 源泉徴収税.
From what I read, this means that I don’t need to save up to pay 所得税at the end of each year as this already covers it.

A few questions came up:

1) I still need to do 確定申告 at the end of each year, right? I’ve already applied for the blue one at the beginning of this fiscal year.
I guess I just have to fill out the field with how much 源泉徴収税 I paid?

2) if I do the shinkoku and list my work expenses on there, is there a chance I’ll have some of the tax given back to me if it (=what was withheld at the source) exceeds the amount I was actually supposed to pay?

3) unrelated, but how do I know if my job (drawing) falls under one of the 個人事業税 categories? I’ve googled and it looks like artists don’t have to pay it, but it still says that things like design industry are an exception and they do count. I’m not sure who decides or how that my drawing job (animation) is considered to be within the “design” field?

Any help will be greatly appreciated.

by zhuzhu09