It does lock, but the cycle can be paused so you can add or remove items from the cycle. It is recommended to not put anything in after the initial rinse has ended. It gives specific details about this in the manual.

Yes. You can hit the pause button towards the beginning of the cycle if you want to add more clothing to this load, but later on, the door stays locked even if you hit the pause button.

Yes the door locks during the entire cycle. However, pressing the "Start/Pause" button will stop the washer and release the lock if you need to gain access to the wash drum.

Yes, this model does have a delay.

Machine has a pause option if you need to stop wash for any reason.

Yes

First off is your washer plugged into a 20 amp dedicated receptacle? It should be.

There are several reasons - they are usually all electrical related for your house. but if you try the unit on another circuit - use a heavy duty extension cord. at least 12ga - but if it happens on a different circuit - you might have a bad motor.

Check your electric panel box. You need a 30 amp breaker for the electric dryer and a 20 amp for the washer. Oh and also check for anything else hooked up to the same circuit breaker that maxes out the amperage. And last thing - sometimes breakers themselves go bad over time and keep popping. I would have the breaker replaced, it is only like $15 at a hardware store and would save you so much stress and frustration if this is the issue. I had a similar problem with an electric stove, was about to send it back to the store before a friend who is an electrician suggested to try a new breaker - everything works perfect for more than couple years now!
Hope it works good luck!