Most Xterras have a front tow hook in the location shown in the second photo in that thread, all SE models do, and it was part of the Sport package on the XE models (w/ fog lights, LSD, couple other things) as well. The little open circles you refer to are NOT tow points, they're tie-down loops. They'll hold up to minor assistance pulls, but are not suited to real recovery duty.
You can also mount hooks from full-size Chevy trucks there:
http://frontier.bigpasta.com/Front+Tow-hook.pdf
For the rear, it doesn't matter if you have your spare in place or not, that hook setup shown is fine.
Otherwise, I have been using the following setup for years now with no problems:
It's an oversized 5-ton shackle/clevis, it can be ordered from Ace Hardware, or buy it online here:
http://www.farmhardware.com/SuperSto...ProductID=8350
Brent