으)면

You attach 으)면 to the end of a verb or adjective stem. If the stem ends in a consonant, use으면. If it ends in a vowel or 'ㄹ' consonant, use면. For example, '가다' (to go) becomes '가면' (if you go), and '먹다' (to eat) becomes '먹으면' (if you eat).

Yes, (으)면 primarily means 'if' or 'when'. It indicates a condition or a circumstance. For example, '비가 오면' means 'if it rains' or 'when it rains'.

No, (으)면 is typically used with the present tense verb or adjective stem to talk about a condition in the future or present. You would not attach it to a past tense form like '갔으면' to mean 'if I went'.

만약 (manyak) also means 'if', but it's an adverb that can be used to emphasize the hypothetical nature of the condition. (으)면 is a grammatical ending. You can often use them together for stronger emphasis, like '만약 비가 오면' (if it rains).

Yes, just like with other conjugations, some irregular verbs follow specific rules. For example, verbs ending in 'ㅂ' like '돕다' (to help) change 'ㅂ' to '우' before adding (으)면, becoming '도우면' (if you help). Verbs ending in 'ㄷ' like '듣다' (to listen) change 'ㄷ' to 'ㄹ', becoming '들으면' (if you listen).

No, (으)면 is a conjunction for verbs and adjectives. To express 'if it's a noun', you would typically use '이라면/라면' (if it is a noun). For example, '학생이라면' (if you are a student).

'Good' in Korean is '좋다'. Since the stem '좋' ends in a consonant, you would add '으면'. So, 'if it's good' is '좋으면'.

Here's one:
시간이 있으면, 같이 영화 볼래요? (If you have time, shall we watch a movie together?)

Yes, it often implies a result or consequence directly linked to the condition. For example, '이 약을 먹으면 나을 거예요.' (If you take this medicine, you will get better.)

(으)면 itself is a neutral grammatical form. The formality of the sentence will depend on the politeness level of the verb ending you use in the second part of the sentence. For example, '가면' is neutral, but if you add '가면 됩니다' (if you go, it's fine) it can be polite.