A person can be Intubated for up to 14 days or as long as needed.
However it's not good if a patient needs to be Intubated for 14 days or longer and sometimes means that the patient is not gonna survive.
Most patients are not Intubated longer than a few days to 14 days depending on why they needed Intubated.
No you cannot and won't be able to talk while you're Intubated.
For one when you're Intubated you're usually sedated and asleep and are mostly unaware of being Intubated and also the Intubation tube passes through your Vocal cords so you won't be able to talk until the Intubation tube is removed.
When a person is Intubated the person is given general anesthesia and a muscle relaxing medication to prevent any pain and discomfort from the Intubation.
However some people have experienced a slight discomfort when they are Intubated but it's not really bad.
If it's a real emergency where you will need to be Intubated then you may be Intubated while awake but if it's that serious then the pain is the least of the worries because without Intubation you could die.
So I would take some pain of the Intubation over dying.
Intubation is an Invasive procedure so it's normal for some discomfort or pain to be experienced sometimes.
Most times a person is asleep when Intubated though so it's not too painful.