Great information Abel.
By now, customers of Tesla should be well aware of the Tesla policy and stop the incessent complaining. Once Tesla gets your order they will go radio silent until they have a need to contact you for delivery. They have no desire to give constant updates, as they know that circumstances often change during production and those updates are often in-accurate.
The program is for you to place your order, then go away and concentrate on other things. Do not obsess over when your car will come, as that is not productive for anyone. Get your affairs in order so that when the call comes, you will be able to consumate your deal.
Pricing is fluid, options are fluid, availability is fluid, configurations are fluid...everything is subject to changes, including expected delivery dates.
This is the Tesla way...get over it.
In many ways it is similar to having a child. The expectation is that in 9 Months you will see a happy, healthy baby to raise as you wish. Of course along the way, many things can happen. Gotta roll with the punches. But constantly asking "Is it here yet" will not change the reality that the baby will come when the baby comes.