i'd go with an i7 for the streaming.
Processor:
While an i5 is great for just gaming, if you start using several intensive programs at once, it is nice to have more computing power.
i7's have hyperthreading (virtual cores)
Ram:
dont go under 16 gb (pc1600 should be fine but if you can it doesnt hurt to go pc1866)
Get a 250GB (or 256GB) ssd for your system and all the progs you are installing.
Dont go 120GB (or 128GB) on this one, you dont want to run into space issues on your system drive.
Get a nice 1tb 7200 rpm Hdd for storage (there are some good ones for under $50)
Graphics:
You want high fps, dont skimp on this one!
GTX960 or higher. I recommend the 970, its just a great card. evga has the best customer service imo
if you want to go AMD, there is nothing wrong with that. get a 280x or a 290x (YES, the X is important!!!)
Powersupply:
500-600w should be fine. Corsair has a proven track record. their cx series is a good value. (i have a TX)
Motherboard:
Several good options here, like Asus, Asrock, Gigabyte (i have an Asrock extreme6 z77)
Case:
Personal pref. i like nzxt cases, i own a rosewill Thor v2. make sure they have easy acessable usb/sound panel. the case should support usb3 nowadays!
questions? ask away!