Nitetrain20

Hello all, I am very new to FPV, have a few thoughts and questions that i need help on.

I am thinking about purchasing the following:

1. BetaFPV air75

2. 1s batteries and charger

3. HDzero Boxpro Goggles

Question, the goggles take a 2s-6s battery....How long does a battery last (4s), how many should i get, and do you need another charger? and how do you charge while out at the park?