First, you should be thankful that your parents have taken the time and made the effort to teach you Mandarin. While English continues to be the most important international language, Mandarin is very important and will likely become more important as the years go by. The fact that you are bilingual will help you get better jobs than a monolingual person can ever dream of.
Many people (especially immigrants and children of immigrants) in the U.S. are brought up with situations similar to those you describe. I suggest you speak to a counselor about getting into some ESL classes at your school. If that doesn't work (and you might not be eligible), perhaps you can find ESL classes at a private school, junior college, community center, etc. Finally, remember that there is no such thing as "standard English pronunciation."
Only 40% of English speakers are natives, so we in fact find many different ways to pronounce things. It is highly unlikely that a person from Scotland would pronounce the same way as a person from New York; both would differ from a person from Mississippi, and the person from India would be different yet. Also, a person from Beijing would pronounce differently.
No problem, so long as people understand one another. Two links to get you started. You should also speak to your English teacher at school.
Try to find out what areas you have difficulties, and ask for extra work on those areas. Unfortunately, this will probably be grammar, which may not be what you need. However, if you are concerned about getting adequate test scores (such as SAT), grammar is probably what you need.
To improve reading comprehension you have to read a lot. This will also improve your vocabulary. There are free web sites that help English language learners.
Some even allow you to send a recording and a teacher can help you with pronunciation. You can also find English language CDs and DVDs at most bookstores or your library. Listen to those, repeat what they say, and try to pronounce in the same way.
Record yourself so that you can hear how well you do.
I looked over your question 3 times and did not find any grammatical error. You have excellent writing (a lot better than some adults I know). It might be just your accent that you're worried about...? If you're watching shows in English, in school speaking and listening to others - I think time will solve your problem.
You'll be able to pick up stuff that you would normally pronounce wrong. Anyways, I wouldn't worry about accents so much. There are many people I know with thick accents who I understand perfectly.
Also, try asking your friends to correct your English once in a while. I'm sure they won't mind at all! They should understand because they'll think you just want to sound a bit more fluent.
Hope I've helped :).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.