I'll answer what I can and hope other, more knowledgable people pick up the slack.
I have the 18-55mm kit lens and it's very good. The XF lenses are of a better build quality than the XC lenses but I've heard very good things about the XC ones, especially the 50-230mm. The advantage of the XF over the XC kit lens, other than the build quality, is speed. The XF is f2.8-4 whereas the XC is f3.5-5.6 and yes, both have OIS. No, the 16-50mm isn't exclusive to the X-T1 as it's the same mount obviously and can be bought separately.
Not sure on the acronyms but WR is definitely Weather Resistant. 'X' is obviously the system, not sure of what 'F' and 'C' actually stand for, if anything.
The 16-55mm is f2.8 all the way through so faster and, as a result, quite a bit heavier.
The difference between the 55-200mm & the 50-230mm is similar to that between the 2 mentioned above, build quality and speed.
All that said, I've just had a look on WEX and they're offering the X-T10 with 18-ffmm & 55-200mm for £999 which seems a pretty good deal to me.
Hope this helps.