importing used to Canada

Ok I read through the posts and am more confused than ever.
I am looking for a used Porsche Boxster 2000 and have noticed some
from cars.com, autotrader, Ebay and craiglist. Cars here In Montreal
run in the 20-25k range while in the states there are lots in the
14-16k range. Some of the best deals are from private but some really
almost too good to be true deals from texas especially a place called
merchants.com. 16K + 6.1% duty + +-$1000 trasport + GST and QST +$195
for RIV fees, still a lot cheaper than buying locally.
Is there a complete how to on buying across the border? Already looked
at RIV.ca
Here are my questions:
Is there a broker that can search and take care of everything for a
fee?
If I do it myself, how can I make sure I don't send money (either
deposit or final payment) to a private or dealer and never see a car?
Even on Ebay most sellers don't accept Paypal for cars(too expensive I
guess)
How do I protect myself to make sure the car previous owner does not
still owe money on it?
Sales taxes, Is there a way to pay the least possible? Are there any
states where you have to pay there then again at the border?
I have a very trustworthy cousin in New Jersey, any way to use that to
my advantage?
For transport especially from places like Texas or California(far
away) Is it much cheaper to get the car to the Closest Canadian border
or can I get it delivered directly to my house after completing border
papers?
Too good to be true deals: If car passes carfax and seller says there
are no problems with the car, no dents or scratches and interior is
very clean, any horror stories of getting the car and it was all bull?
If so any protection available? If from New Jersey or New York I can
get my cousin to look at it?
Am I missing anything?
Buying new from US seems easier since you are dealing with big dealers
but private dealers or privates seems a little scary....
Please advise needed before I take plunge.