Corrected entry: In the Pilot, Clark's spaceship has an almost shell-like appearance - it looks layered. Thereafter, it is smooth, almost shaped like a rounded arrow head. (00:27:45 - 00:33:00)
Corrected entry: Throughout Season 1 the ages/years in school of Clark, Lana, Pete, and Chloe are inconsistent. Supposedly they're all the same age and freshmen, as Pete states in the pilot episode the football team always chooses a freshman guy to be the Scarecrow, which would make them either 14 or 15. However, they're all seen driving (or refer to driving) at least once, which would make them 16, and Sophomores.
Correction: It is possible for some of them to be driving at age fifteen. Kansas allows fifteen year olds to have a Farm License, which allows them to use farm equipment and drive to and from school. There are some other possibilities as well, such as a Restricted License, read about them at Kansas' Department of Revenue website: http://www.ksrevenue.org/dmvteen.htm.
Correction: The ship is designed so that the outer part we see in the pilot protects Clark in space from assorted dangers, then falls away due to friction in Earth's atmosphere (this can be seen on the DVD opening titles before the menus), which leaves the sturdier inner part intact for crash landing.