what the best display preferences are

Mostly it's personal choice, but I would suggest 99 for 'Total posts to show on one page when viewing a thread in flat mode (default is 10)' if you decide on flat mode. Flat mode gives you everything in chronological order, Threaded mode shows you posts according to what they were responding to. The latter can be a little confusing sometimes since flatliners aren't always careful about what posts they click on for responses. But being in flat mode can be confusing, too, since threaded mode folks aren't always careful about indicating what they are responding to, either. The best thing to do if there is any chance of confusion is to quote, in some manner, the element in a post that you are responding to. There is also a site that gives all kinds of helpful tips for new folks that someone will give the link to. I never remember where it is.