I don't think these expressions should be translated. It may confuse you even more. I'll try to explain them.
1) "I don't talk him about politics because it is like a red rag to a bull."
If you wave a red rag (or a flag, or a cape) in front of a bull, it may attack. Think of that image if you talk to the other parson about politics. "Like a red rag to a bull" describes that kind of reaction.
2) "He takes the optimistic view (perspective) and talks about a _______ skies scenario."
What colour is the sky when the weather is nice and pleasant? ;)
3) "Now that they have read it in black and white, they believe me."
If something (a picture or text) is in black and white, it is clear and perfectly understandable. So this means you have given them very clear information.