First question, your friend is absolutely right.

Second one, you can point it out, but never mention it is a mistake. You can say something like "em, it's very interesting you are doing it this way. If I am the developer, I would do this and this....etc...". And if there are 4 of them, most likely max I will point out are 2.

Third one, no one say good news or bad news. just say news, good news is ok. But bad news, it just sounds weird.

Forth one, the first thing I'm going to is to talk to the manager again because he certainly has some ideas that can lead to a solution. I wouldn't answer to spend time to test it first since realistically that's waste of time.

1. Tell me about yourself 我一般是回答教育经历，工作经验，和特长。但对方的表情很平淡，难道答错了？
就是教育经历，工作经验，和特长这些啊，这只是个热身，也不能出什么彩。Interviwer表情当然平淡了

本文发表在 rolia.net 枫下论坛1. there is nothing wrong with what you have said. It is not a problem that you answered something that has been put on your resume.
2. you can try but be extremely careful. They take what you have done as criticize in many cases. Unlese they ask you opinion about something directly, you don't tell people what they have done is wrong. This is the cultrue difference.
3.YOu don't look forward bad news, only good news. Besides, you should always be confident about your behaviour in the interview, no matter what your real thoughts is. Don't say anything negative about yourself.
4.What they wanted to know is that how you are going to do when you don't understand what you should be doing. Your answer is inappropriate. Bescause they are expecting you go to your manger first and ASK!! Don't assume, in any cases!! Always ask! That's what they call "communication skills". This kind of question may appear in many different form, but the key here is how is your communication skills.

Key point:
1.Always ask yourself "why do they ask this question?"
2.Be smooth which means when you feel you make mistakes, try to be joking around
3.Take your time, be used to this kind of job finding game. Take a notes after interview, make sure you don't make same mistakes next time更多精彩文章及讨论，请光临枫下论坛 rolia.net

At end of meeting, would be just fine if say your pleasure and happy working for/with them
The last point, they should examine your personality more than your technical skill because too general.
Anyway, don't worry about. Recently I have not further news either after 5 larger interviews