Interrupt is an obsolete game term, and any card that had it, is now an Instant, or an ability that can be played at instant speed.
Counterspell was originally an Interrupt, as were many other counter cards. Any of them, that have been reprinted, will now show as an Instant and even if a card has not been reprinted, its Oracle wording will now show it as an Instant.
The first release of Magic the Gathering cards was on August 5, 1993.
You can not. They are not part of Magic the Gathering.
41
A lot
No
Spelling stores
nerdy kids and card shops?
yes it does, but the selection is limited.
60-75 cards,
Magic the Gathering cards dating back to 1993 (Alpha, Beta, and Unlimited) tend to be very valuable. You can get information on individual cards here: http://www.magictraders.com/pricelists/
Either 8 or 15 cards.
You can find tournaments for magic cards at Magic The gathering in San Francisco,Ca or at 2154 university ave. in Berkeley,Ca.