Formation of comets and interstellar dust

Factual Questions
1

As I understand astronomy, planets formed as follows. Heavy elements created in supernova are blown into interstellar space.

Eventually, gasses, including a small proportion of heavy elements, condenses out of interstellar space into clouds that collapse under their own weight and steadily increase in density. Big clouds get hot and dense enough to ‘ignite’ and become stars. Smaller clouds become planets. A small cloud that is near a star has the light elements boiled off and ends up as a small rocky planet like Earth, other small clouds hold on to their light gasses and end up as large gaseous planets like Jupiter.

Fine, but there must be some minimum size for an object to be to condense out as something solid because gravity is a very weak force. Something small like a comet has very little mass – presumably it originated as a very small cloud - but how did it get to be compact? I know that comets do break up from time to time, but they must be reasonably solid bodies to survive the rigours of a highly elliptical orbit and to have the fissures discovered from which they outgas. So, how do comets form?

Also, what about interstellar dust? Unless I have misunderstood, this is made up of tiny solid particles that exist in enormous clouds in deep space. How can a grain of dust form from basic gaseous elements?

2

If the particle size is very small (or even perhaps individual molecules), then comets could get to be quite compact simply because small particles pack closely together easily; there’s no reason for voids to form when the process is taking place in (almost)vacuum.

3

Gravity isn’t the only force at work in the accretion process. While it is responsible for the contraction of the nebula as a whole, once the concentration of molecules builds up beyond a certain point, the particle’s chemical and physical properties take over as the most important factor. Atoms and molecules like to clump together. Uncharged particles can stick to each other with remarkable tenacity. In fact this stickiness is all that permits the elements to exist as solids or liquids in the first place.
Stickiness drives the formation of snowflakes from a cloud of supercooled water vapor, and it drives the formation of comets and asteroids from stellar nebula.