One thing that I would do if you want to improve pronunciation is to get an audio-book, and repeat carefully after the reader. Also try to record yourself and you will hear the difference between your reading and that of the native reader. One thing I notice in English learners is that there are some who have the humble attitude that they still need to learn a lot, and patiently and humbly work on their accent, speaking carefully, and repeating after the native's correction even many times, whereas there are others that focus on speed thinking that that makes them sound more natural. However the speed makes them sound worse, not better, because it does not allow them the time to pronounce each vowel properly. English has vowels whose sounds continually change during the pronunciation of the word, contrary to many other languages which have clear-cut clean vowels. For example if you say 'take' the 'a' is pronounced 'ei' - there are two main sounds there, and a smooth continual change between them. When you speak fast you don't have time to perfect that smooth ever-changing sound of the English vowels, which is what makes English sound like English. It sounds a lot better when someone speaks slowly and clearly pronouncing things carefully than hearing a rocket of unintelligible speech.

Yes, if you ever took an acting class. Actors would adopt an accent to sound like the native speaker. It is very possible. There are people who reduce their accent because they constantly listen to the manner that the native speaker articulates.

Yes, it is possible. Some people don't like it when I say this, but simply learning the language is often not enough to sound like a native, especially when one is no longer a child. You may have to receive some instruction from someone who is trained in accent correction. I took some classes like that for Spanish, not enough to really sound like a native, but I can say that I sound much better than I did before.

Yes, but it depends on the person. Some people I know have only lived here 8 years and speak like a native. Some people I know have lived here 20,30,40 years, and still have a strong accent. I don't know the secret.

Muehhh men, you should hear my broken English in begin when I start my learning process, speaking english like a native sounded impossible to me. My best advice if you don't live in a country where they don't speak this language then watch lots of movies and listen to some music as well you can use some websites to find natives, like one of the best shots is Preply http://preply.com/en/skype/english-native-speakers