>>
Hackers/crackers as we would know them predate the "world wide web" by the better part of 15 years, from about as early as affordable home computers with attachable modems existed - the heady days of Altairs and 300 baud acoustic couplers, as indeed seen in the early 80s film "Wargames" (the kit being used by the protagonist is distinctly 1970s).
The WWW didn't arrive until 1990, and public internet access - up until that point just for email, usenet, FTP etc and generally achieved by dialling into a BBS-like service that also had an oh-so-precious (and often not even real-time) internet hookup - only really arrived in the early 80s (email was around before then, but not in the form we would recognise, and not really accessible outside of educational, scientific and military/governmental institutes) and took a while to take off.
The earliest version of the infamous "anarchists cookbook", which detailed plentiful tales of computer and rather more analogue shenanigans (phone system hacking, credit card fraud, homemade bombs, lock picking, epic pranks etc), both up-to-date (at the time) and "of yore" (reaching back into the 70s and even 1960s when long-distance, off-the-record phone connections were far more valuable things to "steal", and everyone knew the story of the guy who managed to accidentally 2600-dial the white house war room), was mainly typed up on Apple IIs, TRS-80s and other such deeply vintage machines, and passed around on olde time low-speed BBSes and floppy disks (don't underestimate the bandwidth of an envelope full of 5 1/4" floppies when your only data line runs at all of 30cps), the 3 1/2" DSDD (Atari, Amiga AND IBM compatible) version of which was my own first contact.
And, heck, even if we don't have Wargames to look at ... just go watch Scanners.
So to answer the first question: very, VERY yes.
Your second one: theoretically yes. Practically? No chance. Remove the human element, and any AI that hasn't been carefully constructed to be completely benevolent/passive and without any learning/self modifying functions other than error detection and repair, and you might be in with a sniff. You can try locking it down with an iron fist, and that will just strengthen any human or independently-operating AI's resolve to break the shackles you've put them in. If there's one thing a hacker can't resist, it's a challenge.
(Again - go watch Hackers...)
And if we go back to the old definitions...
Message too long. Click here to view the full text.