Don't worry you won't be the only one. It's seems like there's no one else especially since programs like Life Sci and Engineering have 800 people each. But basically what you're going to get first year are huge classes where most of the people your going to meet are in some other science program. Even in the easy first year enviro sci and earth sci courses (1C03 and 1G03) you won't be meeting people in your program since 90% of the people taking these courses aren't even in any Environmental program. As far as the first year profs go you'll be getting Bernier for 1C03 and Padden for 1G03. They're really nice people and really approachable.
Now as for electives it's up to you to decide. Just to let you know electives can be ANY course, it doesn't need to be something outside of science. Plus, you can also take second year courses during the second term if you have the pre-reqs from term 1. What I would suggest is probably just look at what you're interested in and then make your choice, since electives depend on you.
That's pretty short but if you need anything else just reply back
