I agree too. In British English "relations" and "relatives" are interchangeable.
"wohnen" is used for short-term situations.
"Ich wohne bei meinen Eltern" ...because I'm at home for the summer.
"Ich wohne in Berlin" ....because I'm only here for one semester.
"leben" is used for long-term situations and situations for which your intention is long-term.
"Ich lebe jetzt in Trier" ...because I moved here and intend to stay here for a long time.
"Wohnen" refers more to your living arrangements, like when you talk about your flat, your roommates, your rent, your furniture. And "leben" describes your entire life as in your job, your friends, your everyday routines.
For example, when people want to know your new address, as in where it is you physically live, they might ask "Wo wohnst du jetzt?"
When they want to know where you have made your life, they might ask "Wo lebst du jetzt?"
As an answer you might tell them: "Ich lebe in Stuttgart. Ich wohne mit einer Freundin zusammen."
Kin is "mountain" English, mostly only used by those who live in a remote and somewhat isolated region (Appalachia) of the US. However, pretty much everyone would understand what you meant if or when it was used the way you used it. And it does mean relatives, so I wouldn't count it as wrong but it is not commonly used that way.
A relative is anyone who is related to you, through marriage or through blood, such as parents, grandparents, aunts, uncles and cousins. A cousin is specifically the child of your parent's sibling (i.e. the child of your aunt or uncle is your cousin). It gets more complicated when you consider, for example, the cousin of your parents, which is a "second cousin" (I think...the rules get complex)
Basically a relative is someone related to you and a cousin is a type of relative.
A (first) cousin has a parent who is the sibling of one of your parents (the common ancestor is a grandparent to both). A second cousin has a grandparent who is a sibling of a grandparent of yours (the common ancestor is a great-grandparent). A third cousin has a great-grandparent who is a sibling of your great-grandparent (the common ancestor is a great-great-grandparent, and so on down the generations.
The other aspect of cousins, for those into genealogy, is the "removed"s. This happens when the cousins are not in the same generation, not the same number of steps from the ancestor in common (your grandfather and my GREAT-grandmother were siblings, perhaps). If my first cousin and I each have a child, those two children are second cousins (see above). But the relationship between me and my first cousin's child is "first cousin once removed": the relationship between my child and my first cousin is also first cousin once removed. If my first cousin has a grandchild, the relationship between me and that grandchild is first cousin twice removed. A first cousin's great-grandchild would be thrice - or "three times" removed, and so on.
Similarly, if my second cousin has a child - or grandchild - my relationship with that child would be second cousin once removed; with the grandchild second cousin twice removed. Drawing a diagram may help. You can go any number of first, second, third, fourth, fifth... and also any number of once removed, twice removed, thrice removed, four times removed...
That is what you should hear (but see below). In English we call the letter "V" "vee", and use it to represent the initial sound of "violin". The Germans call the letter "V" "fow" because they use it to represent the sound which starts the English word "father". The Germans spell the equivalent word "Vater" - but both words start with the same sound. "Vater" und "Verwandten" each start with a "fow".
And the fourth letter in Verwandten"? English speakers call that a "double-U" and use it to indicate the first sound in the word "why?" (Well actually, some English speakers use it for two separate sounds, w as in the first sound of "wail" or w as in the first sound of "whale". For persons who speak like me, those are two different sounds (the second is "aspirated", sort of like h-wale); some persons pronounce both words with the sound I and my ilk use for "wail". Their "wail" and "whale" sound just alike. Ours do not.)
The Germans call the "w" "vee" (in German "vee" rhymes with "clay", not, as in English, "bee"). English speakers often refer to a Volkswagen car as a VW, or a "vee double-you". Germans also sometimes call it a VW - but in German that is a "fow-vee" (remember German pronunciation of "vee": "fow-vay").
So "Verwandten" should sound to your English-speaker's ear like "Fervandten")
The rules for Junge and Verwandten are different. Junge is a "weak" noun, so one follows the weak noun declension rules.
Verwandt- is a noun-ified (nominalized? I do not know the technical grammatical term) adjective, and follows the rules for declining an adjective; it makes a difference whether the individual referred to is masculine or feminine (the forms for your aunt will differ from those referring to your uncle). It also matters whether you are referring to the German equivalent of "the aunt", "an aunt", or just plain "aunt" without any article or other determiner in front of it, just as it does when you decline "rot" or "alt" in front of a noun. And, of course, it matters whether one is referring to one individual or more than one, i.e., singular or plural. It might easier if you look at a chart.
Here is a URL with the full declension of Verwand- https://www.cactus2000.de/deutsch/nomen/shownom_en.php?nom=verwandter