On the flip side, its like a mining gig, your pretty much running yourself at your limit for weeks at a time, but its generally not a bad gig if you want to make a good income over a short time period, but yeah, most of your social interactions in person will be limited, ($50+ per hour to you is not uncommon once the training wheels are off for some of the gigs I've done for late onsite shifts)
Now the level of complexity you will be working with will be highly dependent on what part of the industry you jump into, but expect a mixture of ladder logic, Boolean arguments, function block based design and finally bodge code,
Being able to read someone else's ugly bodge solution, and either debugging it, or adding functionality to it would be the technician level work, (I have left some scary things out in the world, And suspect my name has been cursed a few times from my early years work) If your doing commissioning, expect you will need to work with changing requirements right at the last minute,
As for why the hours are horrible, When is a company most likely going to want there machinery not running? its generally stuff like 10PM - 3AM on a Saturday night, or short period shutdowns where you only get that time period and no more, when everyone who arranged the job is asleep. (I have been locked into sites because the cleaner went home more than once)