CAR ACCIDENT – WHAT ARE MY RIGHTS HERE?

CAR ACCIDENT – WHAT ARE MY RIGHTS HERE?

About two weeks ago, my car hit the rear bumper of another Honda car
in front in another city when he stops suddenly, because of another
car in front of him stopped suddenly.

My car's front bumper hit his rear bumper. On his rear bumper, there
were two similar scratches/slight dents – one on left, and one on
right, of the rear PLASTIC bumper. He said the right scratch/dent was
his in a previous car accident. He said the left scratch/dent was
caused by my car hit. My front bumper had no scratch/dent after the
accident.

After we exchanged insurance info, he told me that he would repair
LEFT scratch/dent, and the repair would cost about $50. (In my view,
those two scratches/dents can be fixed in about $20 if done
personally). However, a week later, he faxed me ONE and only estimate
from a Honda dealership estimating the repair cost to be $400. The
$400 repair cost is to replace the WHOLE bumper.

While I am willing to pay for half of $400 (for the left side of the
scratch/dent), he is threatening to go to his insurance company if I
do not pay the $400 to replace his whole bumper. He said that his
action to approach his insurance company would increase my car
insurance premium in the future.


QUESTIONS:

1) Am I the only one at fault and need to pay his damage, getting to
close, although he stopped suddenly?

2) Can he just show one repair estimate (which may be the highest in
all estimates), instead of say three repair estimates (for the lowest)
which he agreed first at first and then decided not to get more
estimates?

3) He wants me to write him a cheque of $400 payable to him
personally. Do I have to pay him personally, instead of paying to the
Honda dealer repair shop? I suspect that, based on the slight
scratches/dents, he might just pocket the money himself without
getting the bumper repaired.

4) Can he insist on me paying for $400 for the whole bumper repaired?
If he goes to his insurance company, is my insurance company required
to pay $400?

5) If my insurance company is involved, do I (customer) generally have
an option paying for the damage, and thus (I hope) would not increase
my insurance premium in the future?

Any advice and comments would be greatly and urgently appreciated!