Hello oolong rabbit, i have the same questions you have.
I cant give a direct answer to your question, i can quote you some things i found intresting about kunlun and its energy as also ill share you a few of the things i noticed the few times i did the practice (not sure even done 100% correct). Bare in mind im no proffesional and some of these things may sound weird (and some are yust very hard to explain as experience changes from person to person) . If you find so then do tell !
Ow also really wonna know more about this ling-qi btw ! You have any other signs or description of this energy Lin ?
Tummo also seems like an immensly intresting practice. On wich forum have you found info about tummo-practice ? can you post the link or even pm ?
Its been mentioned in a thread kunlun is a yin practice, as a cooldown i noticed you have to seal your hand left over right over the belly (so yin, yang, yin).
When having to much of the energy in your body you are advised to walk the earth, stamp on it, do gardenwork. (this was a tip from Mantra towards Cameron who practiced kunlun in combination with red phoenix-practice)
On the red phoenix website (
http://www.risingredphoenix.com/subjects.html ) about kunlun there is a mention of:
"Further, the magnetic current that one experiences during the practice is not Kundalini, but a more refined form of energy. Basically, one is tapping into the cosmic energy. This energy can sometimes be referred to as ultraviolet-3 radiation, which can only be found in the depths of space."
About Celestial Qigong:
"Celestial Chi Gung is a sitting meditation that allows one to tap into the energy of the universe via black hole."
and
"Technically, a black hole absorbs matter into a rotating vortex of magnetic energy. However, a black hole also emits waves and particles into space. One can use this form of energy for his personal awakening.
This form of radiation from the "black hole" is called ultraviolet-three and is only found in the depth of space, or in objects such as meteorites. This radiation does not travel through the earth because of the earth’s protective magnetic field will not allow ultraviolet-three to penetrate to the earth's surface."
...
Personal experience with the energy itself :
The kunlun exercise has a much more profound/powerfull effect when done at night (around 12 maybe a bit later) try it. Remarkable.
When doing kunlun it seems that the energy comes out from the ground, enters the feet/legs to go upward. It feels like from earth to sky so to speak .. im intrested to know people's experience with this.
I have a collection of very old keris (wich are made with a piece of meteorite) wich emit an immensly strong amount of yin. Kunlun energy doesnt seem to be the same though, it feels more subtle (although this can be an impression as i dont know surely yet how it feels when kunlun energy becomes toroughly packed/concentrated in a very small area). Also kunlun energy seems "inteligent" in another way, as the book says it very well knows what to do inside the body. (This gives me the impression its a littlebit harder to work with or cultivate, again yust a thought).
When i asked a male friend of me to feel the energy comming of my hand after only 10 minutes of kunlun he describes it as intense radiation of heatlike energy (like a stove) .. he had serieus intention of pulling he's hand away. On the other hand when i let a female friend of me feel the energy a day afterwords (after about 15 min of kunlun) she described it as very cold and windy .. she told me it felt like a radiator blowing cold wind between our hands who where 2 cm apart from eachother.
I dont know what to think anymore lol but it surely stays intresting. When i do kunlun for longer then 15 minutes i have to put of my tshirt and sweater, the heat is killing me .. well not killing

more like nourishing but still its kinda warm.
Kind regards !