I believe 2 (building up a vocabulary) is quite important as well; I know many people with good vocal English skills but very poor vocabulary and it can be hard to have a meaningful casual conversation with them because they simply don't understand the subtle differences in meaning between synonyms or even worse, don't even know them. Which makes it hard to express complex ideas or emotions.

And it gets even worse when they (non-native English speakers) speak to English people who instinctively try to use their usual English humour and then feel confused because their conversation partner doesn't get or misunderstand what they're trying to express.