I'm looking for a tool or set of tools that allow, as simply and easily as possible, for the following kinds of word frequency tests to be performed on a relatively large set of textual data: (i) ranked quantification of most frequently used words in a textual archive; (ii) plotting such things over time (i.e., how word frequencies rise and fall over time, as the dates of the individual textual items in the archive progress); and most importantly (iii) collocation tests identifying and ranking most frequently used words within, say, 25 or 50 words, of a target word specified within the textual archive (e.g., what's the most frequently used word with 25 words of "Tolstoy"?)
Thanks much for any help anyone can provide.