@AP115 

I will answer your questions below:

How do I turn off just the wifi but have wired line still work?

Open your Deco app, go to the bottom right icon, then go to Wi-Fi, on the next screen you can disable either the 2.4GHz or 5GHz band. If you try to disable both you will get a message that at least one band needs to be enabled to manage the Deco. 

How do i turn it off and on remotely? 

You would follow the same procedure above.

Is there any way to increase the speed on the 2.4mhz band?

There is no way to modify the wireless setting as far as channel and channel width. Best thing to try is to move the physical location of the Deco so there are the least amount of obsticles to obstruct the wireless signal.

Are there any features or settings I should be using for my home use that I may not know about or are not part of the default settings? 

There are quite a number of FAQs here that I would recommend looking at to see if one subject catches your eye: https://www.tp-link.com/us/support/download/deco-m5/#FAQs

When I run a speed test on my phone through a speed test app separate from the deco app, I am getting drastically different numbers then with the deco app.  Why is this?  What speeds can I trust?  92.8mbps vs   (testing servers were different however had similar results with same server).  473.1mbps

The speed from the app is what the Deco is getting from the modem. What you see on your phone is the data going going from your phone to the Deco. Speeds will vary on the phone depending on distance, the device itself on what it is capable of, what wireless band it is on etc.

What else do I need to know about this thing?

Pretty much anything to do with the Deco is done through the app. I would recommend just messing around with it to see all the various options it has.