I think you don't need to learn Hanja for sure until intermediate level. You can consider when you want to reach very very high level in my opinion. My suggestion is, if you're interested anyway regardless how much you can get, I advise that you learn Hanja focusing more on the "Korean" sound. For example, I saw from another person's (italki) notebook this word: "강추템". This actually is a informal abbreviation of "강력(히) 추천(하는) 아이템" = "strongly recommend/I would recommend item. Here, "강" is a Hanja meaning strong (強), and 강력=強力. ("力" means power). 추천 (推薦). 아이템 = "item" written as it sounds. But as a native Korean by myself, I will be able to write those in Hanja(Chinese) only for 力 (simplest one..) probably I can recognize 強 but I can't write out of my memory. (probably I could.. if I were younger when I learned it long time ago). So Koreans also don't know them all. But most of Koreans know "강" can mean "strong" in many cases. So knowing some frequent ones can definitely help. Example: 강심장 (Strong Heart) a TV show... is actually in Hanja. 強心臟. "心臟" means "heart" "心" alone can mean heart too but there are certain patterns when it comes to the use of Hanja.. for example, we don't like (I think Chinese too) using only one Hanja for a separate word. So traditionally, we call "heart" by "心臟" not "心." They're kind of like Latin for English (right?) like... pre- / con- / anti- ...but Hanja seems to be more deeply integrated in Korean than Latin in English. I think you can memorize some easy ones first. 一, 二, 三, 四, 五, 六, 七, 八, 九, 十 일, 이 삼, 사, 오, 륙(육), 칠, 팔, 구, 십 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 日: 일(day) example: 일일교사 一日敎師 one-day teacher ... 敎 means "teach/teaching" 師 means "teacher." Like above, we use two words to form "teacher". 名: 명(name .. or for person-count) example: 지명하다 指名하다 nominate ... 指 means "finger" 主: 주(main, king, lord) example: 주된 목적 主된 目的 main purpose

Not necessary, but very useful once you get to a higher level. You will see it in novels and newspapers and it will help you with vocabulary. So it depends on the individual - maybe for you it's right or maybe not. Enriched vocabulary by seeing connections is always a plus though :)

If you want to get past TOPIK lvl4, you have no choice. I'm not saying that it is impossible to get TOPIK lvl6 (C2) without Hanja, but it will take lots of time, roughly living in Korea for over 10 years. Learning Hanja is THE fasttrack for higher level TOPIK, and it will add so much depth and accuracy to your vocabulary in addition. And a huge headstart when learning Chinese or Japanese is a gerat bonus, too.

安寧하세요? It is up to your Korean level, curiosity, necessity, etc. If you want, you can try several words. It does not matter whether you should master those. When it comes time, you will make a decision. Decision itself does not make perfect, though. 感謝합니다. 韓國語 學習에 漢字가 必須的인 것은 아닙니다.