Main Deco - M5

Satellite Decos - 2 x M5

Connection - Ethernet backhaul (1Gb)

Switch - 16 port Gigibat Easy Smart Switch (tl-sg1016pe) with 12 ports utilised (TVs, Fireplace, Cameras, printer etc)

The main deco (M5) is in my office and the primary one for the quite a few of our devices and needing the most range/speed.

1) I was thinking of upgrading and replacing the Main deco with a Deco X55 and using the existing M5 as an additional satellite.

Keen to understand if this would be a good step up or any suggestions on alternate models. If below doesn't work I was thinking just a Deco X20.

2) I note that the Deco X55 has 3 ethernet ports. 

Can I simply connect 2 of 3 the ethernet ports from the Deco X55 to the switch (other connected to the modem) in order to improve the connectivity on the ethernet backhaul and devices connected to the directly switch? Will this simply work or do I have to enable Link Aggregation on the switch?

Any insights would be appreciated. Thanks!