Молодец does not mean a "good job", it is literally how we call people who have/had done a good job. So "Молодец" is Someone who has/had done a good job. If you say "Молодец, мне нравиться" it would also mean "good job, I like it", but you would tell this to a single person only, while "Молодцы, мне нравиться" to people.
I think that a literal translation of мне нравится is "To me it is pleasing", so there are two hidden nouns which do not appear in the suggested translation - the dative form of I/me and 'it' which is the subject of the reflexive verb. Sometimes, though, the words we have to translate are phrases or even single words and do not form full sentences.
well, молодец is a noun, although a weird one.
but in russian, you can omit pronouns, and you often do, because verbs take different forms for each one. so, often times you can tell who someone is talking about, from the form of verb used. you don't really need to hear a pronoun to know who I'm talking about.
this kinda doesn't apply in past tense where the verbs are much simpler.
It's pretty clear though... I mean молод and млад really look alike first (м л д)
And it's even clearer with the accents: молоде́ц so the first O is like a shwa and the second like an A. A shwa, even in English, tends to (almost) disappear (there are millions of examples I guess but like 'generally' that is actually pronounced as /genr(e)ly/, even though it might not be the best example ^^)