Yes Kumquat Trees do naturally lose their leaves especially after a hard freeze.
Just like other trees that lose their leaves in the fall and winter the Kumquat trees do as well.
Kumquats can grow just about anywhere but for the best growing conditions the Kumquat trees should be grown in places such as California or Florida where there's no harsh winters.
The Kumquats that are grown in the US are grown in the state of Florida and California.
That majority of Kumquats grown in the USA are grown and harvested in Florida and California which have ideal growing conditions for Kumquats.
When eating a Kumquat you eat the whole Kumquat including the skin.
There's no need to peel the skin off a Kumquat before eating the Kumquat because the Kumquat skin is edible and very nutritious for you.
If you want to peel the skin off of the Kumquat you can do so if you want or if you do not like the taste of the skin of the Kumquat.
But if you want to eat the skin of the Kumquat there's no need or requirement to peel the skin of the Kumquat like you would some other fruits.
I always eat the skin of the Kumquat because there's vitamins and nutrients in the Kumquat skin and you get more health benefits from eating the skin as well as the Kumquat.