1) An SSD is always a nice option, and yes I believe they are worth the extra money. Right now a 250gb SSD like a Samsung 850 Evo or a Crucial BX100 will run you less than $80(USD), a great value.
2) Yes, it will easily handle new games. Black ops 3 for example a user averaged 80 FPS at maximum settings:
https://www.youtube.com/watch?v=MQiEJxyb8v4 (he had a slightly better i5, but it doesn't make too much difference)
3) The case comes with 2 fans, which is pretty good. You of course can add one or two more if you want some better airflow and temps, but I wouldn't say it is necessary. Because this GPU is a reference cooler they actually perform better when the case is under positive pressure (helps them to blow more air out the back) so another 120mm fan up front is always good, but I wouldn't expect anything extraordinary. Don't put fans on the side, in my experience they make temps worse.
4) Yes installing fans later on is usually fairly easy. Sometimes they can be in an awkward location and it can be annoying to work around the CPU cooler or hard drive bay, but it's nothing to write home about.