Time needed every day: Stats
Install and configure:
I believe I am average at technical stuff, and it took less than a hour to have Xav up and running. The config stuff will require more time, since you need to tweak many variables and experiment with your own set of data.
Except for indexing every time your content change, there is very little effort involved (actually nothing, just checking stats, maybe)
Xav has a page with reports about searches. It is not very different from what you get at Freefind, just a little more information (All searches, Single words, Full strings, Time of the Day, Day of the week, Average number of results and this kind of stuff).
Time needed every day: