All those tubes/rilles formed 3+ billion years ago, so the probability of collapse is pretty low. From a radiation perspective, a lava tube is an ideal place for a lunar outpost. Unfortunately, there are none anywhere near any potential polar ice deposits...
Keep in mind the moon still has seismic activity. Proof of this in prior times (might not be as relevant today) is all the inner terraces of older craters which are downslips or slides. Newer craters have, of course, smoother interior walls.
There are moonquakes, they're just very low intensity...
According to New Scientisthttp://www.newscientist.com/article/dn18030-found-first-skylight-on-the-moon.htmlA way has been found into a lava tube;"The hole measures 65 metres across, and based on images taken at a variety of sun angles, the the hole is thought to extend down at least 80 metres. It sits in the middle of a rille, suggesting the hole leads into a lava tube as wide as 370 metres across."Instant radiation shelter!
Scientists report in Nature Geoscience that it [Kaguya] saw exposures of rocks rich in the mineral olivine in concentric rings around craters.They suggest that large impacts could have penetrated the Moon's outer crust, bringing into view the mantle olivine stored just below the surface.The observations are said to fit well with ideas about how the Moon formed.Current theory holds that Earth was hit by a Mars-sized body early in the evolution of the Solar System, and that the debris thrown into space by this impact coalesced into the Moon.The sequence of mineral crystallisation in this ball of molten rock would have seen olivine (a magnesium iron silicate) produced before more dense materials, causing it to sink deep into the interior.But this then led to a gravitationally unstable body with those more dense materials eventually displacing the olivine. As a consequence, the Moon's mantle, it is hypothesised, underwent an "overturning", in which the olivine was transferred to just below the crust.