1. I think I am getting to understand what is confusing you. I didn't critically look at the image in the OP

But if you are looking for the answers to the small value, I marked with a rectangle



Then it's the percentage price change between the open and close price of a single candle on a given time frame. If it's a 5-minute chart, then that small percentage change represents the price change of Bitcoin in those 5 minutes, represented by one candlestick. If you hover your mouse on each candle stick, the value keeps changing.

2. I did some small research and apparently trading view shows the 24 hours change as price from the market close of the previous day (00:00 UTC) even for cryptocurrencies despite crypto markets being open for 24 hours. It's an adjustment many people have tried to ask from tradingview, but It has remained ignored.

However, other tools such as coinmarketcap, coingecko, coinalayze and crypto exchange top gainer and loser rankings base on the 24-hour time interval and not tradingview's format

This graph is for illustration of the 24-hour interval that's always used in crypto markets