I just heard from my friend that all those FUSE apps are not needed anymore in Mavericks. Is that true? I have, from the previous version of OS X: MacFUSE, FUSE for OS X, fuse-ext2, NTFS-3G. Do I still need them? If not, how to remove them completely?
MacFUSE is no longer being developed, and there's many bugs with it in Mavericks. FUSE for OS X was the continuation of this development and still works well in Mavericks. I recommend that you uninstall MacFUSE and instead use FUSE for OS X.
ntfs-3g in Mavericks requires this install procedure:
You should know if you need FUSE — if you don't need it, there are official removal instructions: