Just look at focal lengths.
Crop factors and equivalency really don't matter very much if you're not using two different formats. That a 14mm lens on a 1.65 crop looks like 21mm on a full-frame doesn't help you if you don't know what 21mm on full frame looks like. The crop conversion thing is only going to be helpful for you if/when you add an FX camera body to your arsenal, and you realize you're going to need a lens that does, say, what your 18-55 does on your D7000, so you know the focal length range you want in an FX lens has to cover 27-83mm (18-55x1.5).
If you only have the single camera body, then just judge the scene coverage of a lens by its focal length. The shorter it is, the wider it goes. You may also want to use a focal length simulator that can show you what specific focal lengths look like on a DX body, if you're having trouble visualizing because you've never used those lengths before.
In my experience, an ultrawide zoom is much nicer than a prime if you aren't sure about focal lengths and are new to using ultrawides. When you get down to the smaller focal lengths, a single millimeter change in the focal length can be a much larger change than you're expecting, and you can't get the same perspective by simply walking forwards/backwards. Just my opinion, but I'd definitely save up for the 11-16/2.8 over the Samyang/Rokinon 14mm if I were shooting a crop body. I'd only go for the Samyang 14 if I were shooting full frame and knew I needed/liked that focal length and didn't mind the PITAness of an all-manual lens with no electronic communication; otherwise, on full frame, I'd probably save up pennies for the Tokina 16-28/2.8 or an OEM 16-35.