Yes, the SVR210 and the ADC-VC727P are compatible with each other
Alarm.com recommends the TP-Link TL-SF1005P (4 PoE ports @ 67W total power)
SD Cards are not included with the camera but they are recommended as a backup incase the SVR210 or the hard drive have any sort of malfunction. The link below has a list of recommended security SD Cards
If you use four ADC-VC727P with the TP-Link TL-SF1005P POE switch, you do not need the Smart Gateway as the cameras will communicate to alarm.com through the ethernet wire which is providing both power and internet.