The E3-1231 V3 is 3.4GHz, so it'll perform exactly the same as your i5 in tasks/games that don't utilise more than 4 cores/threads. The Xeon will only benefit in anything that utilises hyperthreading, because that's literally the only difference between the 4670 and E3-1231 V3, other than the Xeon not having an iGPU.
8GB RAM is still fine, doesn't need upgraded but newer games have started utilising more RAM, 16GB is the sweet spot these days and RAM is fairly inexpensive now anyway. You could add another 16GB if you want, but it's not necessary. You could just spend $20-$30 for a 2x4GB kit, and add it so you're running 4x4GB, for a total of 16GB.
If you're getting a new keyboard, get a Strafe/K70 from Corsair, if possible. Or, if you want to stick with Cooler Master, you could look at the Master Keys Pro L(or Pro S, if you don't mind a TKL).