1. Agreed with 2nd floor 1050Ti will suit your need !
2. PSU 600W should be more than enough if you only choose a entry level display card 1050Ti
3. There is no specify ram for this motherboard, just normal DDR3 ram will fit but 4 pcs of ram running in quad channel would be recommended.
4. If the heatsink is really fit and you are "NOT" going to OC, E5-2670 is not hot! Only 40 deg at idle and 55-60 on fullload (room temp 25) Switch to water-cooling seems not wise especially H55 with 120mm cooler. Normally cooler under 240mm for water cooling is just for fun