Not saying math is wrong, below is just drilling down for better protection.

VOICE/TEXT APPS: (for security)

Signal Private Messenger https://signal.org/

*This only works if both parties are using the application, otherwise is means jack s***


NOT ADVISED APPS: (not for hobbying/security/privacy)
These all fall into the same boat, they collect PII, such as your original phone number, telephony logs, messages, etc. and they will share them with LE with a subpoena.

As an example, this is directly from TextNow's privacy policy:

User communications: When you use our Services to make and receive telephone calls or send and receive messages (including voice and text messages, video, and pictures), we are required to collect telephony log information (telephone toll records) like your calling-party number, receiving-party number, forwarding numbers, time and date of calls and messages, duration of calls, routing information, and types of calls. Your messages are also collected.

The other listed apps below have the same or similar policies and are not safe to use if you're wanting security and privacy.

WhatsApp
Snapchat
FB Messenger
Telegram
Textfree
FreedomPop
Google Voice
TextNow (meationed above)


BURNER PHONES

In most use cases "burner phones" as people picture them won't do much to increase privacy or security. This is basically useful if you are trying to hide the activity from a significant other, not LE. These phones still have standard software, MAC addresses, and ping towers just like your regular phone would, all which are trackable. Flat out 90% of people purchasing these don't know how to properly setup the device to use as a burner which would require at minimum a modified OS to allow spoofing the MAC Address, GPS location, etc.

As a correction:

To run other applications network traffic through the TOR network, use ORBOT, not ORFOX or TOR

For browsing, utilizing the TOR network, Andriod users can either use TOR for Andriod, or ORFOX. iOS users closest options is probably Onion Browser.

In short:

If you're using your RW phone, best options are ORBOT & Signal for text/phone, Tor for Andriod, or ORFOX for web stuff. iOS users, just Signal for text/phone. Onion Browser for web based stuff.

Burner phone is the same. If you don't know how to set one up properly, just use ORBOT & Signal apps for text/phone. Tor for Andriod or ORFOX for web stuff.

Stay away from the virtual stuff, especially Google Voice. Setting up an actual useful virtual app requires knowledge about crypto-currency, and making annoymous purchases that many may not have.

Extra Tip:
Get a app that can spoof your GPS location, disable all google location history and sharing, disable improved accuracy for location.

Personal opinion:

Conduct as much of the activities online as possible. Use a VPN or Tor Browser to get on the internet (one or the other, don't mix the two), establish a secure email account i.e. Protonmail, use that for accounts on hobbying sites. Ensure that any communications are trashed and deleted after they're no longer needed. # & address can be exchanged using Signal.

Information, use it or don't