New sellers are sometimes targeted by buyers but as your item was to be posted special delivery it was an unlikely target as this form of delivery is quite secure.
When your buyer did not pay you should have opened an UID after 4 days. After a further 4 days you could have closed the case and got your fees back.
Since you requested a cancellation you are stuck with the fees and your buyer can also leave feedback if they wish.
Their address does seem odd but as they did not pay you will never know if their PayPal address was valid.....it may have been legitimate.
Fully understand why you were so nervous. If you do decide to sell again and hit a problem please try to come to boards for advice first. There are some very experienced respondewho who can give you great advice ( much more knowledgeable than me )