Chances are that if you don't get a M.2 SSD with it your not going to get connection. Main port 0 is SATA 3 2nd port is SATA 2. So yes put your SSD in the main port and use your old hard drive in the 2nd slot for data. To add RAM you have to match the RAM you already have Timings and Voltage
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro