It has been a long time since I have had to use all of these items at the end of a letter; therefore, I'm uncertain of how many spaces to leave between each and the order they should go in. Example:

Jimmy Smith

2 spaces?? JS/jd

2 spaces?? Enclosures (capital E or lower case?)

2 spaces?? cc: Harvey Johnson

This letter must be correct, and I simply do not remember how these should go. I greatly appreciate any assistance.

I don't know about spacing but this page may answer at least some of your questions:
what about the end (typest initials)