Titan facts and questions

To start this I will just ask one question that has passed through my head before:

Do titans burn? As in, does their skin burn as hard as a human's? Does it burn better? (I somehow doubt that) And when the fire got through the skin do they explode?

Feel free to ask your own questions/ideas about them or just discuss others' ideas.

Heya. Let me give my two cents on the matter, based entirely on show-only canon.
First of all, what a wonderful question! Super interesting.
I think in order to answer it correctly, we must answer the question 'What are titans made out of?'. Alas, that is something that we do not know, but we can try and answer.
We know that when shifters turn into titans, they create large bodies for themselves out of seemingly nothing. This, of course, is scientifically impossible. Furthermore, we know that the bodies of the titans are surprisingly light.
Given these two facts, it is a pretty safe assumption to believe that the titan bodies are made out of some form of condensed air, or specific gas.
This is useful information, because we know air is required for the oxidation effect A.K.A burning. Other pure gasses in air are also extremely flammable. This, generally speaking, points to titans skin being very flammable.
However, that comes with a cost - because titans are made of material that just isn't very dense, there isn't a lot of matter to be burned, meaning they'll be burned out completely in the matters of a couple of seconds, a minute top.
So far, however, we completely ignored the titan's regenerative abilities. We know titans have extremely high body temperature, and that they have blood. Therefore, their liquid blood has an extremely high boiling point. I doubt a fire that isn't huge could boil such blood. In that case, considering that somehow the blood also won't be flammable, is it possible to assume that the titan's blood would put out any burning throughout the body?
Alas, I don't know the answer to that. To me, it seems fire would easily be able to engulf a body part of a titan and burn it out completely, before being put out by blood and the linb growing back in time. If titans were truly this vunreable to fire, each cannonball would basically kill them instantly, so they must have some way of dealing with it naturally somehow.
Hope anything I said made sense.

You call what I did with the horses awesome? Duuude...
And almost everything you said made sense
The thing I did not get was the canon balls, as they are not...on fire, neither should be too hot (I might be wrong with that, I am not an expert on temperatures of canon balls).

Going by this Link it says that those canonballs have a temperature of around 150°C, which would not be too hot to be honest...so fire might still work.

The question still is how long it would take to burn through the skin

It's true that a classical barbaric cannonball would have little to no impact on a titan. However, I think it's safe to assume humans use more modern, explosive cannonballs instead, ones that explode on impact.
It makes no sense to me that humans would use standard cannonballs on titans, considering their resilience to most pain, ability to regenerate, and small weakspot.
As I said - my approximation for a burning through a specific area of titan skin is probably just a few seconds, considering how quickly gas can catch fire and spread.

And well, yes...so my idea with using titans as train fuel does not work then....disappointing

Oh well, sorry did overread that with the skin then...