Depending on what "very good" really is, 20-400 USD
made by Colt in 1918. not unusual to see a springfield slide on a Colt frame
Call Colt.
You will have to call Colt with the sn to find out.
about 1978
IT IS A 1957 MODEL OF THE COLT DETECTIVES SPEC .38
Not really.
Depends on the model
yes
Would need serial number to answer or look it up at proofhouse.com
Don't know price , but produced in 1970
10-450 USD or so
What year/spec mustang? A '65 6 cylinder would be slower but a '69 428 Cobra jet would probably be faster.