What about a dormant black hole that isn't bound to any galaxy or star system. Where no matter is falling in, would those be easily detectable..
The universe is never completely empty, even if there's no active accretion disk there's still matter falling into black holes and giving off X-rays. An inactive black hole can be effectively impossible to detect at the ranges they actually exist at, but at the sort of range that would pose a threat to Earth gravitational effects and X-rays should still give it away.
Would it have to be earth like in mass to create the resonance. Could it be a gas planet as well, or since it's so far away, an icy world is more likely?
WISE's survey means it can't be a gas giant, it would have been easily detected. WISE didn't rule out a rocky or icy planet in that range, though. The mass range that would explain the orbital resonance is estimated around 1-10 Earth masses. An icy world is most likely, but a terrestrial object might be possible (it would challenge our model of how solar systems form, but no more than many exoplanets do on a regular basis). Either one might challenge our classification system again, as well, since the term "dwarf planet," would start to look poorly chosen. The only criteria separating a dwarf planet from a major planet has nothing to do with size, and this hypothetical planet would probably not have cleared its orbit, meaning it would be classified as a dwarf planet. Having a dwarf planet kicking around that's larger than half the major planets would come off sounding absurd.
Are astronomers and physicist puzzled with the fact that H20 seems to extremely abundant in one form or another. How do they propose the first molecule of water came to be during early star formation after the big bang, or is water a relatively newer molecule. Can water be created in the vacuum of space or is it bound to celestrial object?
Water's pretty easy to generate if you have the ingredients, pressure, and a spark. The dominant theory right now is that this happens in protoplanetary disks. Young stars blast off powerful solar wind in their early phases, which we've seen compressing and heating disks enough that water should be able to form. The Herschel space telescope has been looking for the precursors of water in various star forming and star remnant nebulae, and found evidence that CO molecules are being broken down by UV light, and the freed oxygen is reacting with hydrogen to produce various charged hydrogen-oxygen molecules, which aren't water, but can react to create water.
So, yeah, in short, they are somewhat puzzled. Water's already everywhere, and they've found water precursors forming in a lot of different kinds of places, but the link from precursors to actual water hasn't been observed yet. As mysteries go, it's not up there with Thorne-Zytkow objects or the 102 second gamma ray burst in 2006, but it is big enough that we have a space telescope on the job.