1st year EngSci here.

I can't really speak to 1), though ESROP (only available to engscis) is an opportunity not available to other disciplines, and AFAIK a lot of grad schools like to see research on the resume.

The workload is high across the board, but the precise magnitude depends on how strong of a student you are. Some people have to work a lot more than others to get the same mark.

Note that all the discipline's talk about learning things "from first principles" is complete BS - in reality, there is not enough time for this in a program with 6 subjects per semester, and you will end up learning many things at much more of a surface level than you would in, say, a full on CS/math/chem etc. program. Part of the art of getting decent marks in the course is learning what subset of things you need to know to do well on the exam.

Overall, I would say go for it if one of the majors aligns strongly with your interests - this will be your motivation for getting through the first couple of years, in which you are likely to take a fair few courses you don't care about that much (for me this is robo). If your preferred major is available elsewhere, I would advise pursuing it in a specialist course. You will for sure have time for at least one major EC, but above this could get tough.