Storing power is not as easy as it looks. If you have a good idea let us know. Huge batteries are expensive and lose their charge over time. You could use the power to pump water higher and then use that potential energy later. There are so many convertions of energy that make it not effective enough.

It's about not having to operate your own datacenter anymore. (not having to pay for electricity, cooling, multiple system admins, and keeping up with your server requirements...) You get an account with a business who has a big cloud. You tell them what kind of equipment you want to use (i.e. via an internet application) and it gets set up for you automatically (within minutes instead of days/weeks/months. Then you just pay for the storage you are using and the processor clock cycles that are used. You pay less, and benefit is that you can easily add more servers (in case you website gets slashdotted)

Teleportation at the speed of light would take 3.3 ns (3.3e-9 seconds) to cover a distance of 1m. This is certainly measurable. However no time difference has been measured in this experiment because the teleportation is instantaneous.

Experience. Before you start do a guess on how long it will take. Maybe divide the problem into multiple parts and try to think how long you will have to work on everything separately. After you have finished the task make sure you write down how long it actually took and compare it with your estimates. Your estimates will get better and better even after just a few projects.

It was probably set to stop listening after a few seconds to make the demonstration easier.