Okay, starting with 1070 variations - there isn't much difference between the 'customised versions'. The big names are MSI, Gigabyte and ASUS, and most offer more cooling capabilities and slight overclocking, so pick the one that you like because in my experience there really isn't much to tell them apart. I would recommend one of the custom ones, since they usually offer much better cooling which will help keep your card healthy in the long run.
The only thing to note is make sure your case is big enough to take the 1070 as it is quite large, I think it covers 2 vertical slots so just be sure it will all fit - maybe measure inside the case just to be sure.
Your processor and ram will be absolutely fine so no worries there. Unless you are keen on overclocking you don't 'need' a water cooling system, and even if you do want to overclock fan coolers are more than capable. The Hyper 212 evo is a very popular and effective fan cooler, one that I use and would happily recommend, I've never used a water cooler and have had no issues at all even under heavy load. Of course it's up to you, and if you definitely want one either read reviews online (amazon reviews are always good as you will get a good number so you know it's reliable), or maybe someone with more knowledge than me can recommend one.
The only other thing I would consider is an SSD for your Operating system - this isn't necessary and moving the OS across can be a pain but you will notice the difference in the time it takes to boot up the pc. I went from a minute or so to about 20 seconds, which you learn to appreciate very quickly! Just a thought, like I said you won't have any issues with the one you have now.
Hope that helps, if you have any other questions just ask!