U2415 is more of a all-round monitor like my U2412M.
Image reproduction and viewing angle are not as good as a good IPS monitor for photo editing but still beter than average TN.
It is not as responsive as a TN but still faster than average IPS.
It comes with an adjustable foot and good build quality.
and...16:10 ratio is my favorite, I do not quite like 16:9.
For such price, I would have bought 2 or 3
For the SSD,
I own 840 and it is great. I believe 850 should as good as 840 or even better.
But for the price, I would stick with 840 EVO for now.
An SSD is also considered as a must although not obligatory in todays high-end rigs. Your rig will be a lot more resposive with an SSD.