There is not a lot of data on dragon mating and reproduction. What is known is:
There is no way to tell what type of breath weapon a dragon has except by provoking it to attack (which is not recommended) The dragons ability normally matches its habitat The three most common abilities are as follows:
fire:
There are three main theories to how dragons breath fire:
1. they produce a hypergolic substance, which is a substance that ignites on contact with air.
2. they produce 2 substances which are combined in the mouth as the exhale.
3. They produce a flammable "venom" which is released through hypodermic fangs. the venom is ignited by a piece of flint and a piece of iron which is made to rub together inside a small pouch in the bottom of the mouth to make a spark, igniting the venom.
Ice:
the main theory is that they get nitrogen or some other refrigeration gas that is compressed in a second stomach. When they attack, the dragon releases the now liquid nitrogen, which rapidly decompresses, and quickly absorbs the surrounding heat.
Acid:
this one is the simplest. The dragon "spits" acid from his stomach.
A dragons anatomy is strange. They are the only creature ever disscussed that has an intenal skeleton to have six member (four legs and two arms.) The membrane of a dragons wing is like that of a bats. the rest of their body is reptilian.