Just to clarify a couple of things, in society programs there are two different types of electives
1) Complementary Study electives (6 units worth), these are the ones with a specific list of courses because of Canadian Council of Professional Engineers Accreditation requirements. The idea is that these courses are supposed to focus on humanities / social sciences and give future engineers a broad perspective on society.
2) Focus electives: (18 credits worth) specific to society these electives can basically be almost anything and allow you to minor in a program or have some broadened field of study. As has been said by other posters in similar threads, essentially you're required to submit a plan / outline of why you've picked focus electives. You can choose to try and use them to get a minor, but you don't have to. What the society program wants to avoid though is people just taking random courses without a goal / theme.
So on your questions:
4th year anthro: no reason it can't count for a focus elective, but would have to be approved by the dean for a complementary studies elective
Bio: no idea sorry
Env studies: appears it can't count for CS elective (likely because its science based) but again, no reason it can't count as a focus elective as long as its in your plan.
8 hours: is hard but reasonable as long as you have sufficient breaks. Having long periods of time without classes on other days will give you a good chance to find a place to study and get a solid block of work done.
If you can't fit a minor in the 18 credits of focus electives and 6 credits of CS electives, you can always take an extra course or two one summer to get enough credits to fill up your minor. And finally, you should contact the engineering advisors to get definitive answers on all your questions.
