The trash compactor and detention block layout aboard the Chimera being the same as on board the Death Star. Simple nostalgia? No. The Death Star was a super-secret military project, hidden as much as it was able to be in normal military expenditures. So it makes sense the Death Star would use standardized parts and layouts, like those for Imperial-class Star Destroyers, wherever possible, to keep costs in both construction and design down.
In the 20th Anniversary annotations, Zahn notes getting some flak for describing ysalamiri as "creating bubbles where the Force ceases to exist," especially considering how later entries would describe how essential to life itself the Force is. Zahn's defense is that Thrawn is the only one who offers an explanation for the ysalamiri ability, and might well be wrong. But there's actual evidence in the story that ysalamiri aren't "pushing back" the Force, but more like jamming it. Vornskyrs hunt through the Force, and the more Force-Sensitive a being is, the more they're attracted to them. In the jungle on Myrkr, where the ysalamiri are affecting the Force, the vornskyrs can still sense Luke (and once, Mara) as strong in the Force. Indicating ysalamiri evolved 'Force-jamming" to try and hide from vornskyrs, and vornskyrs evolved a way to pierce that jamming.
