Mth DCS explorer - Remote commander Help

Will the DCS explorer Wi-Fi do this for both at same time or do you need 2 of them?
Yes. The two loops will have to both be connected to the Explorer at the same time. You will not be able to electrically isolate them. If you do use two explorers, you can separate the loops electrically and still run your trains with one app.

Will the remote commander do this for both at same time or do I need 2 of them?
You will need to Remote commanders and the loops will have to electrically isolated to run each engine independently. Be sure that your DCS engines have been factory reset to ensure they will have the proper engine address to work with the Remote commander(s).

If needing 2 can I get same kind or should I get 1 of each?
You can run these together or independently of each other. Just remember that the power needs to pass through the Explorer to the track in order for it to work properly. The Remote Commander can be run "Passively" by connecting the output leads to the track and letting whatever power source you currently use to power your trains.

Note: I do have the Lionel Legacy Remote system.
Again, the DCS explorer must have your transformer power connected to it and then the Explorer powers the track. There is no passive option with the Explorer. This is all still compatible with legacy but may not be ideal for powering your track and trains. Running the Remote commander in passive mode is okay but if you run two, the tracks need to be isolated electrically.

Should I consider waiting and buying the new Wi-Fi wiu coming out?
This might be your best option as it will be the most robust device that will give you the most amount of features and multiple ways to provide signal and/or power to your layout.  Your Legacy system can also be plugged into the the WTIU and you can run your legacy engines with the MTH app.