Can iTunes pause a specified amount of time after a particular track? It's possible to get iTunes to start a song in the middle, say, after a long introductory section. (This is great for party mixes, where one doesn't want to interrupt the energy of a mix.) 

In a similar vein, is it possible to get iTunes to pause for several seconds after playing a song? For example, in an album of several associated pieces, it would be nice if iTunes would pause for around 30 seconds after the last movement of one piece and the first of the next piece. (All within the same album.) This would be particularly useful for classical music, where each movement is its own track, but several such pieces are jammed onto an album.
You're asking two questions here. 


  It's possible to get iTunes to start a song in the middle?


Yes, for each individual track, you can press CMD+I (get info) and get to this tab:



Where you can check Start Time, Stop Time or both and specify a time. 
Part of a Gapless album is useful too, since it will not leave a gap time between tracks (nice when you have live albums or such).-

*Is it possible to get iTunes to pause for several seconds after playing a song?*


This is not natively possible within iTunes and you'll have to perform further research, try to find an App that does it and/or create some sort of Applescript. But doesn't seem like something natural to do, so it may not be easy to achieve (automatically).

A simple trick you could employ is to record a 30 second silence (you can probably find them if you google, it's used for ringtones) and play that in between your playlist.