You might consider general purpose software for qualitative analysis such as ATLAS.ti, MAXQDA, NVivo, or Dedoose, but I suspect you would be better off with a program that is specially designed for linguistic analysis.
Nvivo is the software most people I know use for corpus content analysis but I think wordstat may be more suited to looking at sentence structures and syntax.
Have you looked into Voyant? It's a suite of tools developed by digital humanities scholars. Also Tapor (tapor.ca). I was recently told about Stanford's POS tagger (http://nlp.stanford.edu/software/tagger.shtml). However, I lack the coding chops to make full use of it. Perhaps you can! Good luck.