Hello to everybody,

I am very new to BTC but want to learn.

I have Electrum 2.9.2 on my desktop computer.

Let's say I have 3 different address with 50$ on each.

I want to go to an BTC ATM machine (Genesis type) to have 75$ cash.

I suppose that the machine will give me a QR code on its screen to send them the required BTC.

Obviously, I will not bring my heavy desktop computer.

1- Should I download Electrum for Android on my mobile phone?

Let's say so.

2- On Electrum for Android,

Option A- do I create a wallet with my Electrum desktop seed and have everything (3 address), or
Option B- do I create a new wallet?

If I create a new wallet,

3- Do I sweep 2 address from my desktop to 1 address on my mobile.
Please, explain the process of sweeping.
Is it my Electrum desktop that begins the sweep process or the Electrum mobile?
Do I have to sweep all the address or, what I would like, only 2?
And can we sweep the 2 address at the same time?

OK, let's assume now, that I have 100$ on my Electrum cell phone.

On the ATM machine, I scan the QR code, send the money in BTC and get my 75$ cash.

Now, I have about 25$ (let's forget the fees) on an new «change» address.

If I have Option A, does the mobile wallet synchronize automatically this new «change» address with the desktop wallet?
If so, do I have to, next, delete the mobile wallet for security?

If I have Option B, do I have to sweep this new «change» address to the desktop wallet?
In this case, the mobile wallet would be empty for security.

Ouf, c'est tout!