Yes, a Jennings J22 will fire without a magazine inserted.
50 or so
Recommend you ask a gunsmith for help
used about 125 (like new) - 50 (worn) dollars us. New about 150.00 Us.
Around $50-$60
Best to ask a gunsmith for help if you don't have a manual
.22 LR rim fire
That's a task best left to a gunsmith.
$50 to $75. These were very crude, low cost firearms of no particularly high quality.
No more than 100 USD
About $150, and not made in the 1950s. 1990s, maybe
$50-$80. Low cost firearm, company no longer in business.