1.

I have seen something like this before, where somebody sort of "embedded" their own OS into a web browser.

2.

The UI looks old, and vintage, however there are a few bugs and visual issues. When I try to, as example, move the icons left or right, they sometimes stack on top of each other, or the movement just does not work at all. Also, when you have multiple tabs open, and then click on a different tab, the icons get on top of the icon.

3.

Adding the windows icon, and making more OS dependent features, such as more Apps, task manager, solitrare, minesweeper, would be fun additions, and interesting projects to take a look at.

4.

They seem somewhat outdated, especially looking at the projects app, or at the about app. Also, yes, they are very vague, and do not explain you personally. I know you said that this was a hobby project, but the design is well enough that you could send it as application, though then you would need to improve the text aswell.

1.

Yes

2.

Yes, but i don't like that you have to double click to open. It's not intuitive, you should change to one click or a comment.

3.

I would think on an animation.

4.

No