Correct, though you'll often see it misspelled as two words. Please report it.
The big picture is that "weg" is a separable prefix in other tenses/contexts....."Er geht weg..", while apparently not in this tense
The term ‘trennbare Verben’=“separable verbs” is a bit misleading. In the infinitive and participial forms (e.g. ‘weggehen’=“to go away”, ‘weggehend’=“going away”, ‘weggegangen’=“gone away”), separable verbs are never separated; in all other forms, they are always separated.
When a separable verb is separated, the parts aren't merely separated into two words; what was the prefix becomes a particle that always comes after the main part of the verb.
Correct. It's consistently mispronounced throughout Duolingo's German sentences.
"Trotz" is the preposition "despite" (it takes a genitive object, e.g. "trotz des Wetters"="despite the weather", though it's now frequently used with a dative object, "trotz dem Wetter".) "Trotzdem" means "despite this/that".
what is wrong with still he went away? How would you say that differently in german? thanks
That would be "Er ist schon weggegangen." Trotzdem=in spite of (it/something)