What is a lifespan of quarks, what will the temperature necessary to maintain them from forming protons or neutrons
According to my very limited understanding of particle physics, you need a temperature around 2 x 10¹²K to sustain a quark/gluon plasma. Up and Down quarks are I think stable, but the other quarks can change into one another under various conditions. I don't know the details, I'm afraid. I expect someone else can tell you more.
Top quarks decay spontaneously because the universe has a much lower energy density today than when top quarks didn't decay often . . . ? You have Feynman rules for up quarks decaying to down quarks and vice-versa. You still have one quark in, one out, but you also get decay products, e.g. photons.
If I understand you can rise the temperature for short period of time but as the temp. drops from the excitation it falls back to its stable state. As in the CERN experiment , due to collision quarks were produced but they were not able to separate them . So did they collapse into protons or some formed a heavy quarck of a mass of tungsten ?
I note there's a difference (possibly arbitrary) between spontaneous decay and scattering. The latter is what the LHC does--scatter protons off protons. But, the detectors detect decay products. I suppose I can say (since I'm not a particle physicist), that protons decay spontaneously into decay products of various types, when they scatter off each other with sufficient energy. Maybe someone should email a relevant question to an actual physicist who knows more about it.