I want to build a gaming PC? - 2

So it's time I've joined the PC master race. Ha. Always wanted to say that, alright so I've been wanting to get a gaming pc for a long time now. So I need some help. I don't have a single clue what I'm doing, so I'm asking if anyone knows a good build or just regular computer (absolute max $400) I want to run games like GTA 5 or FO4 or cod/boyfriend and minecraft or terraria, you know your normal games. So if I could get some advice or even an entire part list it's all greatly appreciated, thanks!

Adds pop up when I left click in minecraft?

So when I left click a white page shows up then I see the desktop for about half a second then it goes back to the game. I do play other games but it only does it in minecraft?

How to update mine craft to 1.8.8?

Yes, I know this is the stupidest question to ever exist, but I went to the website and clicked on the link at the bottom, but there's no button for updating, thank you for the help

Can you remove creative mode in Minecraft?

My daughter loves Minecraft, but she only ever plays in creative mode. I d like her to play more in survival mode so that she can gain a bit more out of her gaming time. Problem solving, planning, etc. She is so timid that she doesn't want to do anything even slightly difficult, so I'm trying to force the issue. Looking for single player solutions.

Is Linux better than Windows?

I want to install Linux on my computer but I don't know much about it. There are a lot of questions about it: can I run games like Minecraft, The sims 4, The Sims 3, GTA, counter strike and need for speed? Can I make websites and programs on it? Can I do same things like on Mac and Windows? Which Linux OS do you prefer? Is Linux hard to understand? Is it good for gaming? What is Linux good for and what I can't do on it.