How to translate "passionate"?
热情：enthusiastic, warm
多情：affectionate, loving
热情 is fine, but 热恋 (fiery love) is better for your sentences. An alternative is 激情 which literally means passionate with a sense of excitement.

The two of them are passionate lovers. 他们是热恋中的情人。
They are very passionate in bed. 他们在床上充满激情。
She gave him a passionate kiss. 她给了他一个热情的吻。