習慣 と くせ はどう違いますか？説明が難しい場合は、例文を教えて下さい。

> I read くせ has a tendency to mean "a bad habit" while しゅうかん is neutral.
It's more like:
Usually しゅうかん used for positive/good habits/customs while くせ is neutral.

> しゅうかん can refer to custom (something that people do that is traditional or usual) while くせ doesn't have this meaning.
Yes, that's right.

> Is there anything else to know about these two terms?
Since しゅうかん could be the formal word of くせ, you should say わるいしゅうかん when you talk about bad custom(s) in a formal situation.