Vyolence

Well the i7 build has the better CPU and GPU, so I'd go with it if you can afford it and are willing to pay for it. There's nothing wrong with pairing an i7 with a 1070 or pairing an i5 with a 1080, by the way.

Yes, they will be better. But this better is not what you might consider significant, some years ago, a new generation would make the previous generation nearly obsolete because the advantages of the newer processor were so obvious. Now to see some concrete improvements you may want to skip 2/3 generations. 

Edit: all pics moved to the original post

The difference over skylake will be pretty small. From what we know right now it seems Kaby lake won't offer much of an ipc jump at all (probably less than 1%) but due to the use of an improved 14nm process the mobile Kaby lake parts at least are more efficient and thus have higher clock speeds than skylake. We don't know if Kaby lake will be much better than skylake on the desktop, though. It might be possible that as frequency goes up the different between Kaby lake and skylake shrinks or it might be possible Kaby lake can reach clock speeds skylake can't.

Yes it will.
PCIe is backwards and forward compatible with every generation.

I recommend an RX 470 for ~$165 from jet.com.  Or if you want best performance in the category, get a ~$230 GTX 1060 (after using promocode triple15).  The 1060 is 10-15% faster in dx 11, and costs 40% more.  You have to decide if it's worth it. There's also the rx 480 and 1060 3gb, but I believe the 470 is the best price to performance, and the 1060 6gb is the best overall performance. 

The measure of a good boss is one that gives credit to his/her team, notice you said our and not my. 
 
Btw feels weird putting a full stop after the word my

You're not really going to get the phone for $150. You'd be getting it for $150 upfront and then paying a huge amount for it over 24 months. It's pretty much always cheaper to buy the phone outright and then buy a SIM plan. 
 
I'm not too familiar with how American phone contracts work, so I can't really answer the second question. Over here, if you upgrade, you also agree to a new contract, so you're still paying for the phone that way and can't exit the contract without paying the full amount (if you exit 12 months into a 24 month contract, you generally have to pay the remaining 12 months and a cancellation fee). 
 
I very much doubt you can trade in two, unless you want two 24 month contracts for two iPhone 7s. 

It's Chinese not Japanese, and the symbol is for RMB. Currently 7.51 to an euro, making the list price around 320 euro.