I grew up in Montreal, Quebec. There are two uses of "c'est chaud" that I've heard used in a "slang" sort of way. The one I heard the most when I was younger was sort of like saying "Oh snap!" or "Holy f--- that's awesome!"...usually accompanied by the finger snapping thing that was popular in the 90's....
Not quite that musical, but you get the idea.
Now in my "advanced" years, I hear it used more often as the "that's a tricky situation" type of expression.
Short explanation: (Almost) every noun in French needs to have an article in front of it. Du can be translated as some, but it doesn't have to be.
Long explanation: Du is a partitive, like de la and des (which is also a plural indefinite article, but that's another topic). If it had to be translated into English, it would likely be translated as "some". However, it is often omitted in English, like in this sentence:
• Je mange du poisson.
In English, that sentence would mean "She is eating/eats fish." It could be translated as some fish, but the some isn't required in English. However, in French, an article is required in front of (almost) every noun, so the partitive article du is used.
More on partitives: Partitives like du are used in this context (where they would replace some in the English translation of the sentence, if the sentence had some). However, they can also be used to mean "a part of". For example: • Elle mange de la tarte. She is not eating the whole pie (unless she's really hungry). She is only eating a part of the pie.
I hope that helped, even though the long explanation is very long!