Xvesa.tce in the extension area is of the same version as the one in Slitaz, built from xorg-server-1.2.0. It is a different build, just same version. It should have the same functionality as the one in Slitaz, numlock LED and all, and should be configurable through the Xvesa setup tool. I would like to know if there are any issues with it versus other Xvesas.
The larger Xvesa, as well as Xfbdev, remain as extensions because of their size even though the newer Xvesa may support more hardware, and some laptops will not do X at all without Xvfbdev. The same principle applies to wireless. The purpose of the base iso, of course, is to function as a launchpad to build your own system tailored to your needs. Some essentials will have to be loaded as extensions. We try to support as much hardware as possible, just not through the base system. This degree of modularity takes some getting used to, but it has it's advantages. Hope this helps.