Actually, I believe it does have the vipw, chfn, and other related commands, but they don't matter, because OSX doesn't look at flat files (/etc/passwd, /etc/master.passwd, and so on). It uses a system called lookupd so store information on system users.
It does have a command-line utility called niutil to create/modify/delete these keys, but unless you're use to them, it doesn't make a whole lot of sense. Also, the flat-files may be used in case OSX can't start and you go to single-user mode, so it's probably a good idea to enable the root user and keep your flatfiles in sync with lookupd.
As for ports, they're not officially supported by anyone (especially not apple!), but there is a project called Darwin Ports, and they're using the FreeBSD ports collection, and in turn porting them over to Darwin.
Here's one of the many sites about it:
And another smaller one:
On top of that, a slightly more promising project called Fink is doing a similar thing:
Either way, it's a damn cool system...
And yes, it was pretty