Dell Warranty Questions

I have a dell xps laptop and many other dell desktops and other laptops previously bought many years ago. 

I believe if you don't buy warranty,, you get 1 year warranty included in price right?

Now what i want to know is this.  Do most of you buy warranties for your laptop?  Say its a 1500 dollar plus laptop  If you buy warranty, how many years do you buy and what is best value?

Now let say your computer has issues not was not your fault.  Like something broke or bios update or things like that.

I know that with other laptop brands i owned, when i had warranty, they ask you to send it back to them and they will either repair it or give you a new laptop... can someone confirm this?  Is dell like this as well?  Say you bought a dell xps laptop and it bricked and they can't fix it.  Or they could.  They usually fix the parts right or put in new parts?

Now my big issue is this.  Let say you have important sensitive or important financial information on your laptop.  Thus you don't want technician to access it etc.  Does dell ever allow you to return the laptop but you remove the hard drive for safety reasons?  Or they always require that?

The other thing is how long does it take for them to work on your laptop before you get it back?  Say it takes 3 days for them to receive your laptop.  I mean you should expect them to take at least 7-14 days to work on my laptop at minimum right?  Then when you get it back... you basically will be without a laptop for at least 3 weeks?  Is that about right for ppl who return dell laptops and get it repaired?

Now what if it was a battery issue that wasn't your fault?  I mean i assume you could send them the battery only right and then will send replacement as oppose to you sending them the whole machine?