I saw your post on cc, and oh my god you have a lot of questions!
For engineering, you probably want to be a biological engineer. (I am NOT in CoE so take this with a grain of salt and be sure to confirm with other people! aka official advisors) The reqs are here:
http://www.engineering.cornell.edu/academics/undergraduate/curriculum/handbook/2010/majors/be.cfm
From my brief glance at the reqs, it is missing only three premed classes: 2nd semester gen chem (4 credits, includes lab), 2nd semester orgo chem (3 credits) and the one-semester orgo lab (2 credits). That's not too bad at all imo.
The 1st year schedule recommended by that site has FWS, intro bio, and math which all overlap with premed/Cornell reqs... I would also recommend considering pushing back something else to take chem 2090-80 first year. If you do transfer into CAS you won't have "wasted" any time at all taking CoE reqs. I do think you should give CoE a shot though, you might like it.
A note about biology classes: If you're considering being a bio major in CAS do NOT take BIOG 1105-06. This can screw you courses-wise over b/c bio classes at Cornell are kind of stupid. If you're 100% sure you're not going to be a bio major 1105-6 is great.
As an engineer it looks like you're completely done with writing/english after first year! But if you REALLY REALLY want to avoid writing you can avoid it in CAS too lol. In CAS you have to do 3 semesters of language (or 1 upper level class if you have previous experience) and 5 "distribution" classes... However this does not necessarily mean english, you can fill it with things like "introduction to japan", philosophy, government, history, sociology....
I don't know about psych majors here but I'm not sure that psych overlaps well with premed. Google their reqs.
As for research, if you aren't shy it's easy to get. (aka if you aren't afraid of emailing/meeting random people) If you are shy no one here is going to hold your hand, you had better go to a small college... The great thing about being big is that there is a great variety of things to do (courseswise as well as researchwise). I started this semester as a freshman in the federal lab on campus, doing research on aphids. I know a couple other freshman who are doing research too, if you want it this early it's easy to get.
As for volunteering opportunities... I'm going for a MD/PhD so I know less about that but I think people go to the nursing home here, transportation provided. It's probably less than in Boston though.