I'm not sure if there is a similar topic, if so, I apologize. I could not find the answer.

I have one question about creating new addresses on Ledger nano s:

For example, I have 10 BTC on address A, which is generated as a deposit address on Ledger nano s.

(Let's just pretend there is no tx fee for simple)

Now I send 1 BTC to address B. But what Ledger nano s actually does is, it sends 1 BTC to address B and sends 2 BTC to address C.

Then I send 4 BTC to address D, and Ledger nano s sends 4 BTC to address D and sends 1 BTC to address E.

Now I can see that I have 5 BTC on my account using Ledger app.

But on address A I only have 2 BTC. I also have 2 BTC on address C and 1 BTC on address E.

Though I have the same private key that can spend BTC on address A, C and E. But I cannot see the addresses of C or E on app.

Here's the question:

1. What if I want to send 3.5 BTC to address Z? How will ledger nano s spend my BTC from these three addresses?
2 BTC from A and 1.5 BTC from C? 2 BTC from C and 1 BTC from E and 0.5 BTC from A? Seems random.

2. And in this creating new addresses mechanism, we protect our privacy better, but does it cause more transaction fee?
For example, if I want to spend all 5 BTC and send to address Z. Ledger nano s has to send all my BTC from three addresses, it seems more fee than sending from one address. I'm not sure if I'm right.

3. If I send 10 BTC to address C or E, can I spend them? I think so but I cannot spend from a specific address, right?

Thank you in advance.