@zachiedoo 

I see that you have selected Deco M4 for your WiFi mesh, which (M4) is WiFi 5 and not even WiFi 6. You hardwire everything, which means you'll be getting max fiber speeds on WiFi everywhere if WiFi mesh supports is. So, the question is: what is the speed of your Internet (fiber) link? If it is faster that 500Mbps, you should consider different Deco model, the one that is at least WiFi6. Such as X50 or X55. If it is faster that gigabit, perhaps also pay attention to speed of Deco Ethernet ports.

To run everything the way you want, you should keep Deco mesh in its default Router mode. This will make Main Deco your new router and Satellites will automatically play the role of Access Points, but under TP-Link terminology all units of your Deco mesh will run in Router mode.

There might be issues with switches compatibility, and with Guest Network support. I suggest you read the following TP-Link FAQ documents:

1. General questions about Ethernet Backhaul feature on your Deco

2. How to extend guest network when there is a switch between Decos

Connecting TPLink Outdoor Access point should work, but it will not join Deco mesh. Even if you configure it with same SSID/password as Deco mesh, it'll run as a standalone WiFi router. 

To have everything on same Deco mesh, you will need to get Deco X50-Outdoor unit. Indoor you could have M4s or other Deco model, they will run just fine together with Deco X50-Outdoor.

  @Alexandre. 

Our internet maxes out at about 130Mbps, so we should be fine with the M4.  Which is a good thing, because they were delivered on Friday! 😁

The managed switch I selected is a listed compatible model.  I contacted TPLink directly about the unmanaged switch and they replied that any TP Link Switches are mostly compatible with Deco's Ethernet backhaul set up. 

If we don't have a guest network, that's not a deal-breaker.  

The Outdoor AP being a separate network is not a big issue for now as we don't have any 'smart' devices outdoors that will need that seamless feature.  If it does become an issue, the X50 looks like a really good choice, so thanks for that.

Very much appreciate your thoughtful response.