No, you don't need to know all the meanings, and you certainly don't need to use them. Be selective, and use some common sense about meanings which you think you will NEED to use. The best dictionaries list definitions in order of how commonly used a meaning is. If a word has a lot of unrelated meanings listed, you can be fairly sure that the last ones in the list are less important. There is also a difference between a person's active and passive vocabulary - the words which you use, and the words which you know but don't use. Most native speakers have an enormous passive vocabulary of words and meanings that they're aware of, and a relatively small active vocabulary of language in daily use.

Oye: Sometimes, the most effective learning strategy is to forget about those things which are confusing or puzzling, and proceed to learn those things which are easily and quickly understood. It can help for a student to master the Dolch Word Lists of the Most Common English words. This lists show the most common 100, or 300, and more words in various classifications. It can help I think, to know the basic Latin Roots, Prefixes and Suffixes. .

Most native speakers do not remember all of the meanings. The figure out or remember the meaning from the context (the other words said or the situation). If you ask the average person to describe all but the most common words they will probably have trouble or have to think for a long time.

Why would it ever be difficult to remember a couple of other different meanings of a particular word ?, when the exact same thing is existent in your own language. If i'm not mistaken a single Kanji or a Chinese character can not only have different meanings, but the same kanji can be read differently in certain contexts.

o(∩_∩)o 哈哈 你怎么不弄个头像？这样看起来怪怪的。。。。