1. Some bacterial viruses are DNA based and others are RNA based.
2 & 3. Bacteriophages look for proteins as entry ways and use biological trickery such as dormancy to fool the bacterial cell into believing nothing was altered. Some bacteriophages multiply rapidly upon entry of one bacterial cell which can spread quickly to other bacterial cells if in a bacterial colony.

He means a triangle placed on the surface of the known Universe would have all angles add up to 180 degrees (Euclidean).

I have heard that gravitational energy can be negative. Whether correct or not I believe this aligns with supersymmetry in that anything that can have a positive charge can have a negative charge or a mirror component.

What are the generators in this thought experiment?

What could possibly happen if c were negative? Any thoughts?