m'ath, zhey vezhof! I can help you with your questions, and I will try to write it easy
1) the
'th is not a suffix, it is a word,
eth, which means
must. You contract it with the
Jini, because it is easier to say
Jini'th than to say
Jini eth. You see the same thing happen in
M'athchomaroon, where that word is easier to say than
Ma athchomaroon.
2) This is an idiom; a saying that does not make sense when translated into another language. In dothraki, when you call someone a flame, that means the same as calling them nobody. It is confusing sometimes, but you will learn soon
3)
Som in dothraki means
none, so they are telling someone that no one else has their name.
I hope I answered any questions you had!