Root canal treatment can be slightly uncomfortable/sensitive/painful during the first seating(assuming the dentist does a good job) and no more pain whatsoever on subsequent seating/appointments if it is a multiple seating root canal treatment.

Most of the time you could but highly dependant on cases

Cases where there was existing infection, I would not recommend biting too hard on that side,

And also do remember in between appointments the dentist will most probably only use a temporary restoration material to cover up for ease of access later on, so eating normally is ok, but not hard food like peanut/bones etc as it would probably cause dislodgement of the filling

Not too long, not too short again its highly dependant on the situation and condition of the teeth, but I would prefer anywhere from 2 weeks to one month at the most for the second seating.

And did your dentist advice on a crown for the tooth after root canal?

Yeah an important part too, because what happens when we do a root canal treatment is 'killing' the tooth to retain its function and functions of its surrounding structures, and the main aim is to alleviate the pain, but with this the tooth becomes 'dead' and tends to get fragile over the years, it's not instant but in years to come the teeth will start chipping off/ breaking off piece by piece.

Therefore a crown is highly suggested to maintain the root canal treated tooth and to save time and money for you(long run). I know crown with a root canal could be expensive, you could opt for a crown at around 1-2 years after the root canal is completed, 2 years being the absolute maximum.

Yep, typically give it around 2-3 months to make sure there's no problem with your root canal, but different dentists have different views so best consult your doctor on that

I did my teeth cleaning at UKM half year ago. Then my molar tooth start feeling pain when get in touch with cold air or water.
I went to a private dental to check. Applied dressing (a temporary medicine pasting?) and ask me to come back after one month. If no pain, will proceed permanent filling. But I went 3 days before the appointment date because i feel pain (suspect the temporary filling falls off). Then they say cannot do permanent filling. They do temporary filling again and ask me come back in half month.
Went to another private dental to check. Told me to either remove the teeth or do RCT.
Went government dental to check. The dentist cannot even found the problem until I told her the full story. Then only she suggested to do removal (the quickest and less hassle way). Only after I told her temporary filling works for me previously then only she agree to do temporary filling and permanent filling on next appointment. (so far I didn't receive any call from them and will not expect them to follow up my case.)

Planning to pay a visit at UMMC or Mahsa for root canal treatment.

Updates:
Paid a visit to Mahsa. Seems like the doctor unable to find out the cavity but still ask me to do RCT. Professional will cost 700-800 while student will cost RM10 per visit but I have to wait until they come back from Semester break.
My temporary filling fall off again, plan to visit UKM again for root canal treament or permanent filling.

MY QUESTION,
IF THE PAIN ONLY COMES WHEN YOU EATING OR DRINKING WATER, PERMANENT FILLING SHOULD BE ABLE TO SOLVE THE PROBLEM BUT WHY ALL THE DENTIST KEEP SUGGEST DO RCT? IN FACT, THE TEMPORARY FILLING DO EASE MY PAIN WHEN EATING BUT STILL FEEL STINGY WHEN DRINK WATER. (SUSPECT THE FILLING WASN'T FULLING COVER THE CAVITY)

Hi,
After extracting my wisdom tooth,  it's impacting my 2nd molar. I was refer to another Doctor from my original clinic since it's difficult for filling and root canal due to my smaller jaw and position for filling for the 1st doctor. I was charged total RM3500 for both services with the 2nd doctor.
1st consultation rm100, Filling rm550 and remaining for root canal.  Is the price normal or is it high due to referral ?

And now will be going back to my 1st doctor for crown, how much usually cost for a crown ?

no one short answer to that. It could be anything you have mentioned

best get it checked with the dentist.