@Gerard_Amatin has a great answer that covers some of the ‘specifics’. However to cover some of the broader “How do they…?” issues from your OP:
Ganking, done right, is profitable over the long term. That doesn’t mean it’s easy or a breeze - just that it’s actually a low-risk, fairly reliable source of income that mostly depends on a ganker taking a thorough and consistent approach to the business of spotting, killing, and looting easy targets.
Since it’s profitable and somewhat reliable, that means there are ‘career’ gankers with multiple accounts, bots, third-party software set to notify them outside the game, etc. As well as corps with dozens or hundreds of members to cover various areas and time zones. So yes, they can perma-camp active areas.
Multiple ways to deal with the status/standings loss exist: buy it off with tags from the profits, earn it back with the various “Increase your standings” services and guides, just trash the char and start a new one, or simply ignore low standings because gankers can take advantage of game mechanics such that they aren’t generally exposed to much danger from police ships etc.
Deciding to be a gank spoiler (known as anti-ganking) can be done, but basically you end up doing as much or more work than the gankers, for virtually no profit, and costing the gankers nothing they weren’t already prepared to lose anyway. So really it’s just there for folks who like to give up their game time just to annoy gankers.
As for shooting the dropped cans, unless the dropping player somehow abandons the cans quickly, you’ll get suspect flags for shooting or looting the containers anyway. Which just means the gankers get to kill you for free. Plus, career gankers will have often have bot alts set up with loot scripts that loot things faster than you can blink anyway.
Not trying to discourage you from anything you enjoy doing, but in the long run, gankers are set up to exploit certain common situations and mistakes other players make, usually in fairly high-traffic areas. That’s what makes it profitable for them. Learn those areas, situations, and mistakes, and how to avoid them. Then you can mostly ignore the gankers and get on with your game.
They like to pretend they’re apex predator pirate bandits, but they’re really just bottom-feeding scavengers. And CCP’s philosophy about the game is that such scavenging is part of the EVE-verse and isn’t going to change any time soon.