Passcode sharing needed for battery replacement?

Hi,

I recently got to know about the iPhone 6S battery replacement program. I booked my appointment and went to the nearby Apple Store yesterday. As mentioned in the mail, I had turned off the 'Find my iPhone' feature.

In the store, the store representative (Apple Genius?) confirmed that my phone indeed qualified under the scheme.

He then told me that it would take 3-3.5 hours to get the battery replaced due to weekend rush.

Then, he asked me to turn off all three options (Unlock, Apple Pay, App Store) under Touch Id. I couldn't understand why that could be needed but I did it anyway.

After that, to my surprise, he asked me either to remove my passcode or to share it with him!

Obviously I couldn't agree to either of those. When I asked him why it was needed, he replied that otherwise I was at risk of losing my data.

I confirmed that I'd taken full backup of my phone before coming to the store, as mentioned in the instructions. Hence, I have no issues even if I lose data.

Then he went in (I don't remember now, whether it was with my phone or not) and came back with the barcode I'd be needing to pick the phone up later. Also, he told me that it won't take 3-3.5 hours now, it would only take 2 hours.

I took the delivery after 2 hours and saw that none of my data was lost. It was just as I left it.

Now, today in the evening, all of a sudden a message popped up on my phone and on my mac that my Apple id is being used to sign in to a device (from an area near to my place, but not my place). However, it could also be because I connected my Apple TV to my TV after a long gap this afternoon. I checked my Apple TV and it did not show anything on screen suggesting that it had requested for sign in.

Now, my questions are,

1. Is it an Apple approved practice to ask customers to remove passcode or to share it for battery replacement?

2. Did the replacement time reduce from 3.5 to 2 hours because I did not share my passcode or was it just a coincidence?

3. Could there have been an attempt for stealing my personal info by the Apple store personnel and it was him who tried to log into my account when I received the message today?

4. Why isn't there any feedback option for Apple Store interactions!?

(I am aware that Apple store engineers might be able to extract all the data from my phone even without the passcode. However, I'd like to be under the illusion that my personal data is safe with the passcode.. :-| )

Thanks,

Kedar