The standy mode on the PLC devices can be turn off through the tpPLC utility. You can find the utility on TP-LINK websites.

Powersaving mode is entered only if the connected device drops its LAN connection - in other words, only if and when the connected device enters its own standby mode AND this standby mode is not a form of "connected standby", like a PC with wake-on-LAN capability. The LAN port on the connected device needs to be truly off for PLC powersave mode to happen.

The answer would more likely depend on how many cameras / what resolution and capture rate - i.e. how total much bandwidth you are going to need. If cost is not an issue best to get the fastest (9020 range) - and update to the 3.2.4 firmware (they are not stable with the currently shipping version). I run 4 x 3MP Axis cameras at 20fps / minimum compression (~ 8MB/s) without issue on those across a fairly large house and have bandwidth to do other things as well.