In a dark time The speaker exclamation in line 13 (a steady ... correspondences ) most clear serves to introduce a series of you observation that illustrate the speaker

no its not a run on sentence however i think you meant wet suits not sours also a run on sentence would be like surfers surf all winter long in southern california by using wet sours to keep them warm and the live their all year long  

absolutely it most certainly can.

c, have a good day ~matya