How to minimize gas fees

When I send BTC from my cold wallet, it asks me to pick normal or fast for the fee. I always pick fast, and it always says 10min, around 5 sat/b. After 10min, it is usually still unconfirmed and not finalized. Only at the 15min mark, was it actually mined according to the display! And it wasn't until the 30min mark that it finally ended. After the 10m mark, it gave new figures for normal and fast after clicking on bump fee. But, I never paid any bump fee.

• Q: Why did it say 10min, when it really needed 30m?
• Q: What did I actually pay for when I clicked FAST - 10 MIN?
• Q: Should RBF be on/off?
• Q: And should I manually finalize the transaction after sending it?
• Q: Why doesn't it let me finalize everything from the beginning?

I want the BTC to arrive in 10min, like it said. The fast option. That is my end goal.