[HELP] Researching for first project - how does my plan look?

Goal: Successfully launch and recover a payload consisting of at least a GoPro

After searching this subreddit I found this tutorial: https://www.tracksoar.com/a-tutorial-for-launching-your-first-balloon/

I think I am going to buy my balloon from here: https://www.scientificsales.com/Meteorological-Weather-Sounding-Balloon-s/25.htm

I am going to buy a tracksoar for GPS coordinates, temperature, altitude, and humidity. I am considering looking for a used chipset, because right now it is the most expensive item.

I will use this website to calculate my flight trajectory: http://astra-planner.soton.ac.uk/

This looks like a good place to buy a parachute: http://www.the-rocketman.com/recovery.html

I think I am going to package the GoPro and tracksoar in styrofoam and weigh the payload. Using the weight information I can size my balloon and parachute.

Some questions I have are

1. What should I use as an antenna?
2. Do I need another way to track my balloon?
3. Where should I buy my lift gas? I am thinking about using hydrogen because it is cheap and I have had a lot of safety training for various jobs (chemical engineer).
4. Will I need an amateur radio licence for the tracksoar?

Thank you so much in advance. I am really looking forward to your first balloon launch stories.