This is a fugue with three voices; when I started looking at this, for some reason I thought the end of the subject was on measure 7...but I afterwards analyzing the piece i looked up the online analysis from timothy smith, and it makes sense. Measures 1-7 looked like a big chunk to me, and this motive was repeated in different voices...but having the subject end on measure 4 makes sense to me now because it ends on the dominant.
anyway, the subject is four measures long, and begins in F major. There are hardly any structural phenomena except for a couple of changes in key and also in register. After the expository part, the parts of the subject break up into fragments (i think they do...?)The two cadences I noticed are very small IAC's (measures13 and 29) that are moving very fast. It modulates to D major around measure 33, and ends on a very noticable PAC on measure 46. Then it moves to g minor right on meausure 47, ending on a very noticable PAC in g minor as well. It sounds really cool. The ending cadence is finally ended with a PAC in the original key. I counted 13 subjects...who knows though?