+1

True

I tried trop mauvais after looking at the dropdown hints and it was marked wrong.

I wonder why people are down-voting this comment; there's nothing inherently wrong or inappropriate about it. This example could be referring to a young adult waiting to gain access to an age dependent trust fund, or perhaps waiting to be old enough to legally purchase and imbibe alcoholic beverages. Maybe someone just wants to be legally considered an adult! Context is everything. Sort of.

If I understand correctly (I might not), vous can refer to many people, as you suggest, but also to just one (it's the "formal" version of you). In that case, you wouldn't need the extra s at the end of adjectives.

"Vous" can be singular or plural. So use "jeune" for singular you and "jeunes" for plural you.

My understanding is that "peu" means "little", but "petit peu" means "very little". So, no, not synonymous.

No, sorry. "Mal" is an adverb, translated as "badly", so that doesn't work grammatically. But you really can't even say "trop mauvais", even though the individual words mean "too" and "bad", because the French idiom is different. I would take "Tant pis", "Dommage" or "C'est dommage", which are equivalent expressions in French. Not everything can be translated literally.