Hi Device,
That mean that the oculus developer kit 2 has as target group developers and not customers. So it have a lower resolution, a stronger pixle grid and perhapes less features than the final customer version
yes, but the optical quality will be in the oculus not so good like when you watching that videos on the screen, because you will also have pixlegrid, which means you can see with your eyes the pixles of the display.
from case to case different, depends how good your eyes are without glasses if you have luck you can use it without glasses, if you have no luck like me for example you must wear your glasses, but there is enough space for that.
the oculus dk2 have a resolution of 960 x 1080 per eye. Perhapes the final consumer version will have a better display, which is to be very likely.
At the moment the oculus rift and dk 2 is just a gadget for normal consumers, which gives you a impression of the immersion which the final consumer product 'could' provide but not more.
So it's on you to decide if it's worth or better to wait ~6 - 12 months to get a final product with that you can play games very good.
i don't know how much shipping costs you have to pay, i live in germany and i have to pay 55USD shipping costs and 76.95 USD fees and taxes and end up with total costs of 481.95 USD