what is the difference between using iyo/yo and ieyo/yeyo? Both are attached at the end of the sentence to make the sentence sounds more polite? so when should iyo/yo be used and when should ieyo/yeo be used?
My suggestion on this one is to send the first part of your question in a message to the user manyakumi -I'm sure he can explain in detail which to use and when.
Also, for i/ga introduce in lesson 24 of newbie season 1, it is used as subject marking particle. Which is the same as eul/reul. Similarly, when should eul/reul be used and when should i/ga be used?
This part of your question has a minor misunderstanding, the marker particle eul/reul 을/를 is an object marker (receives action) not a subject marker.
It may help you to keep these three pairs in mind 이/가, 은/는, 을/를; to oversimplify:
이/가 - plain subject marker (typically, but not always: passive performer/3rd person)
차가 고장났어요 - The car broke down.
내가 거기에 갔어요. - I went there.
은/는 - contrast subject marker (typically, but not always: active performer i.e. "this subject" does such-and-such, or to show contrast as opposed to, or to a greater extent than some other possible performer of said action)
나는 거기에 갑니다 - I am going there. 나는 거기에 갔어요 - I(regardless of some possible others) went there.
을/를 - recipient of action of the performer:
나는 그녀를 사랑해요 - I love her.
그녀는 나를 사랑해요 - She loves me.
그녀가 나를 사랑한댔어요 - She said 'she' loves me.
내가 - I
나는 - I
나를 - Me
그녀가 - She
그녀는 - She
그녀를 - Her
English has no such markers so in the case of "you" so it can be confusing for Koreans trying learning English:
당신이 - You
당신은 - You
당신을 - You
That makes Korean a bit more precise than English, don't you think?