How are researchers trying to answer these questions?
See handout for an example involving planet formation.  But the key points are:
Make observations that are designed to discriminate among competing theories.
Make theories that involve basic physics; add physical effects that are simple at first and only more complicated as they are needed to match the data.  Make quantitative predictions that can be tested.
Interactions (communication) between theorists and observers are key; they inform each other of the next productive steps to take.