Actually the four screws on the bottom were not threaded all the way up. I didn't check to see if the thread gauge was the same on them, but it wasn't until I had about four screws out (I didn't take them out in the order that the bottom all came out first) that I noticed a difference. I then took out the rest of the bottom ones to see if they matched the two that were already out that weren't threaded to the top. They did. So I went under the assumption that those were all bottom screws and when I put it back together everything went fine with no resistance.
So there are three types of screws: Four for the bottom, three long ones as indicated and three others that might be slightly smaller than the bottom ones.
It caused an error upon reinstall of the OS. You forgot to mention that disconnecting the battery would reset the date, and installing the OS without resetting the date would give a general message about the process failing with no mention of a problem with the date.
Getting into terminal mode and typing: date mmddhhmmyyyy will reset the date. The hours and minutes go in the middle and the first mm is the month.