Do the bonus spells activate for non casters? Can a rogue of this race cast cure light wounds and magic missile once a day?
No they cannot, and nor does a Gnome's bonus to casting illusion spells help a rogue either.
The tucker reference has nothing to do with the current racial features. That question pertains to how they deal with combat. Do they have weapon users? Do they field armies?
These creatures aren't all that aggressive, and prefer to keep to themselves. Still, they know better than to sit down defenseless, as they are attacked from time to time, be they from the odd goblin raid, to the Illithids that find their brains to be a wholesome meal. The Ulruun don't despise the Illithid the same way the Githyanki do, but they are wary of them, just as they are wary of others who would attack them.
What kept the Ulruun alive for so long despite such powerful foes is their immense understanding of magic, their innate sensitivity to wisps of souls, and their power of mind, which with some combination of all three sometimes, they are able to evade danger altogether.
The weapons that they use originally came from the outside world of humans, dwarves, and elves, and the Ulruun as a whole are still trying to figure out what use they could be. They figured out that a weapon is necessary for humans, dwarves, and elves for defending themselves as they don't really have the kinds of talents the Ulruun had, still, there are a few Ulruun that have gone ahead of their time to master swordplay. Those few are working on finding a place in their society for this, but so far, the most Ulruuns see of weapon play is as an art form, and not a necessity.
Anyway keeping all four actually detracts from their oneness to external forces, while a rotation reinforces it.
I'm not sure I completely understand what you mean by a rotation. Is it coming up with a list of 4 other racials, and then having the player pick one of them and then going with it? Like I would take for example, Incarnum, and then make a seperate list of racials for it. Then I would take Arcane Magic and make a seperate list of racials for that one too? If thats not what you mean, then please correct me.
Is there anymore physiological, cultural, or historical data on these guys?
I've written a little something in the above paragraphs about that.