Tiranis Q X7

Hi guys, Completely beginner here, maybe with extremely basic questions. Somebody just gave me a Tiranis Q X7 and TinyHawk Freestyle (not sure II or III). Basically new. I even had to change the rotors, because of a positions. I hope Unfortunately a couple things are missing.

1. No screen
2. No battery for the Tiranis Q X7, no battery holder, just a short converter cable.

I have about 6 small batteries for the drone.

I am just guessing, my first step to solve battery problem.

I am looking for a cheap 7.2V 2S battery pack. I saw people use 18650 batteries for the radio and even for the drone too.

My first thought is to have a double 18650 battery holder for the radio and get a charger for the 18650s (4 slot?). A little soldering isn't an issue. And I can use the charger later if I want to the drone also.

I am open to any advice.

(I will need after this , what is the name for it?, a wearable screen. A still don't know if I am interested in this on a long run.