As to your first question, we can answer that. You wrote: what does sufficient physical and existential conditions mean? "Existential conditions" means the specific conditions necessary to exist. Air, Water, and Food and Shelter are such conditions. Physical Conditions refers to basically the same identities. .

Terry: It does not really "mean" anything. The first thing to be noticed is that the author is engaged in wild speculation without any Scientific or Philosophical basis for the speculations as well. The second thing to be noticed is the little word IF at the beginning of the first sentence. This indicates the author's sentences are based upon a Conditional. (The author has no facts for the basis of the speculations, so all sentences are predicated on IF, indicating that it is a slight possibility, rather than a fact. The third thing to be noticed is the speculation about VIRTUAL REALITIES and the author cannot distinguish in his own thinking, the difference between what is VIRTUAL and what is REAL. The fourth thing to be noticed is the claim that "A philosopher thinks in worlds" which is logically absurd. What a philosopher thinks in is "mind". The fifth thing to be noticed is the claim about "a logical possibility of a new world". The author fails to define "world" and there is certainly no syllogistic reasoning in the author's written constructions. The sixth thing to be noticed it the claim that "a new world" will be "posited" which does not mean anything at all in what is called "reality". I could go on and on showing you the factual errors in this author's writing. It is basically a lot of speculative nonsense, constructed by a person who clearly hasn't a clue about either factuality or logic. .