"It is warm, so we are going swimming."
Translation:Het is warm, dus wij gaan zwemmen.
Yes that's ok. I learned recently that apparently this inversion doesn't happen with dus, but both inverted and non-inverted are commonly used by natives in sencences with dus. If nobody abides by this rule, I think the rule should be changed. :)
Warm is a predicate adjective in cases like this, so you don't add the ending.
The rule is something like: The unstressed pronouns can not stand on their own in subclauses. This is sometimes called a "clitic pronoun subject" (a stressed pronoun as a subject).
If it was an audio question, you have to type exactly what it says on the audio.