well, since I was summoned...
for the core classes, monday through thursday is typical, fridays are usually only if they can't fit the class in the schedule or something weird happens. Most people have two classes that are 4 days a week, 50 minutes, and one class that is 3 days a week, 1 hr 15 minutes. Then there is LRW. LRW is changing from 1 to 2 credits for your class year, so I don't know if they will put it in one big 2 hour 30 minute session once a week or break it up into two 1 hour 15 minute classes.
No one knows how the sections are assigned exactly, I think I remember sometime a while ago I heard that they try to make each section roughly equal in terms of demographics, GPA/LSAT, etc. The sections certainly seem roughly equivalent, although they all have their own individual quirks and reputations. As far as what classes everyone will be taking, a lot of that seems to depend on how they can organize the schedule. The small section is logistical hell for the administration since it effectively doubles the number of professors they need to teach 1Ls in the Fall. What ends up happening, of course, is that all the sections are taking different classes - Sections 2 and 4 took the exact opposite classes each semester - which can make discussing classes with members of other sections somewhat awkward, as might be expected.
Pearalegal - you're getting the sections confused with the societies. There are 4 "big sections" of ~90-100. Each big section takes all its classes together, except for the one "small section" class, where the big section is further divided into 4 smaller sections of ~23-25 for purposes of that class and LRW only. Each big section comprises two societies, but the societies only function for social events, and serve no class purposes.