You take it to a gunsmith who has the special tools needed to remove a barrel without damaging the gun.
$100
Depending upon overall physical and mechanical condition, that rifle will be worth, at RETAIL, between $75 and $150.
100-300 USD
$200
100 or so
200 or so
Yes
50-100 or so
100-400 USD
Blue Book of Gun Values
50-200 usd dependingon specifics
25-125 USD or so