I am also a foreigner learning Korean and I think this is complicated too. Something important is that there is a difference between formal language and honorifics. Formal Korean usually has this kind of ending (there are more but here is the most simple version): ㅂ니다 / 습니다 etc Eg. 합니다 (do), 먹습니다 (eat) Honorific Korean usually has this kind of ending (again, there are more): 세요 / 셨어요 etc Eg. 하세요 (do), 하셨어요 (did) The first type, formal language, is used in formal situations such as if you are a waiter in a restaurant or giving a formal speech - foreigners tend to use this in the wrong kind of situation and it sounds a bit weird. The second type, honorifics, are used in day-to-day life when you want to be polite to whoever you are talking to or about (never use honorific expressions when talking about yourself). I think honorific expressions are more important to learn at first. Since formal Korean and honorific Korean are not the same, you can combine them. If you combine them, you can show somebody respect in a formal situation. The ending might look something like this: 십니다 / 하셨습니다 (there are lots of different ways to make formal honorific endings so I am just using the most simple example) Eg. 하십니다 (do), 하셨습니다 (did) As you said, this is very hard for foreigners to learn, but don't worry it too much. First, concentrate on learning basic polite form (~요), and then once you understand this, you can learn more different forms naturally as you progress :)

I think there are may way and I depends. It is the best way to talk with korean. For example, "I'm going to buy something to eat in store " (I don't know it is correct ㅠ_ㅠ) 나는 가게에서 먹을 것을 살 것입니다. But korean usaully say like this 가게에 먹을것좀 사러갈거에요.

you should learn basic form of Korean words, (especially, verb.) basic verbs can be transformed to various forms in tense(past/present/future) and whether honorific or not Let's see this verb, '하다' which means 'do'. 1. 하다(present/basic form) - 했다(past) - 할것이다(future) 2. 하시다(present/honorific form) - 하셨다(past) - 하실 것이다(future) honorifics seem to be hard to understand to foreigners, so thet first thing you should study is basic forms of vocabulary. Watching Korean dramas could be useful to understand either forms we use basic verbs to close friends and family members(some people don't...) except in these cases, you may as well use honorifics. ^^