You can call Remington at 1-800-243-9700 and go thru the menu selection. One of the menu options is to request information on your Remington based off the serial number. You read off your serial number and the guy looks up in the database the year the gun was made and what the original barrel was for that gun (if gun had barrel options like shotguns do).
fingers on the trigger
See related link.
Bottom of receiver in front of trigger
http://remingtonsociety.com/rsa/questions/barrelcodes
$200-$250 if better that 90%.
D081337n
$139.95
100-400 USD
$75 to $250 depending on condition. Express do not get the value of the wingmasters.
$200
The serial number is located on the left side of the receiver, towards the rear, just above the trigger.
It's on the barrel underneath the forearm piece and on the trigger guard as well.