Is it possible to overdose on coffee? I'm asking this question because I overheard someone talking about needing at least two cups of coffee in the morning to "function properly".

Also, they said this while drinking ANOTHER cup of coffee and then went on to have ANOTHER refill ~10-20 minutes later, and all of this was 3-4 hours after they woke up.

Now, I'm no genius, but surely this can't be healthy.

I have several questions regarding the matter:


Can you die from a "coffee overdose"?
What kind of health problems could you get from drinking too much coffee?
How is it possible for someone to need coffee to function, is it like how an addict needs drugs?
If someone who's "addicted" to coffee stops drinking it, would that person suffer from withdrawal symptoms?


Also, for the sake of curiousity, are there any recorded cases of a "coffee overdose"? I've looked around but can't find any.

Thanks.
Caffeine overdoses and even fatalities linked to caffeine overdoses have been reported and a quick google scholar search will show that it is still an active field of research and new cases are being found.
A good overview of caffeine overdose can be found on healthline. Some outakes:

Caffeine overdose may occur if you ingest more than [...] 400mg.
12 oz. black coffee has 260mg of caffeine

Early symptoms:

dizziness
diarrhea
increased thirst
insomnia
headache
fever
irritability

Severe symptoms:

trouble breathing
vomiting
hallucinations
confusion
chest pain
irregular or fast heartbeat
uncontrollable muscle movements
convulsions

Prevention is kinda obvious, but I will quote it for completeness:

To prevent a caffeine overdose, avoid consuming excessive amounts of
caffeine. In most cases, you shouldn’t have more than 400 mg of
caffeine per day and even less if you’re particularly sensitive to
caffeine.

The short answer to your last two questions is that one can be addicted to or dependent on caffeine. In a 2012 study investigating caffeine dependence they found that a staggering 96% of subjects had withdrawal symptoms when taken off caffeine and thus had a physical dependence. The article goes into a lot more detail for each of your questions and has a few more good references. So if you want to investigate further that I would suggest that as a good jumping of point.