Do most students attend the Extension school part-time? I read a statistic of ~8hrs/semester normally, so 2 classes/semester? This seems like a light load-- is it feasible to do 3-4 courses/semester, or is this really difficult, given the challenging course material. What about summer courses- are they more expensive and is financial aid offered?
Yes, 3-4 courses a semester is possible, but you probably shouldn't do it. You need to dig yourself out of the hole with your old GPA and you can't afford to do badly. You need A-/A in every class for a lot of classes to make things up, so don't chance it by overloading yourself. If after one semester, you feel that you can take another class and not suffer, then think about it.
The course material is challenging, so you should have the time to read and learn by yourself as well.
You might want to think about doing quite a bit of volunteering during your time at HES... You'll have a better shot if you can submit an application to a medical school/DO school with "My grades aren't great, but I'm a great, community-minded person..."
Summer courses are the same material in a shorter time, and it costs more. Summer general chemistry is 2 semesters in 7 weeks, and it is hard going. It costs c. $4,500 (most summer courses are $2,250 per semester equivalent). You'll find yourself taking the courses with Harvard undergrads, HCP students and high-school students if you use the summer.
Are all classes at night? Or can you take some during the day? Are these classes solely designated for Extension school/HCP students? Is there any segregation amongst the non-HCP students and the HCP students (as far as study groups, etc) or is everyone pretty friendly and helpful?
Most HES courses are during the night (although I believe there are some daytime ones, but I've never taken any during the post-bacc). It's not the case that you can just elect to do a course in the day OR the evening; it is just given once, in one time slot.
HES courses are solely HES students, of which HCP are a subset (but most of the class in Gen. Chem/Phys/Organic/Bio).
There is no segregation in HES course lectures, labs or tutorial groups. Additional study groups are organised by students on an ad-hoc basis, but they are usually very friendly and helpful. As mostly non-traditional students, people are generally very welcoming.
Are people friendly in Boston? How's the snow in the winter?
Lastly, what's the biggest pro and con about attending the Extension school (probably as a non-HCP undergrad. student)?
Most people complain about Bostonians being less than congenial, but they've seemed reasonable to me for the past year. Winters are cold, but the snow isn't too bad - it just hangs around as ice for a while, which is less fun.
Biggest Pro: It's Harvard and people respect it. It seems silly to say it, and it might get some people's backs up, but it does make a difference in success. It's not easy, but if you can keep up with the top students here, you'll do fine later on.
Biggest Con: It's Harvard and it's not for the faint-hearted. The attrition rate is high. The courses here are harder than your local generic community college. One of the reasons that the post-bacc HCP has a good MCAT average and acceptance rate, is because the poor students have given up before that point and aren't counted in the statistics. Most of the post-bacc programmes do this, of course, but the weeding is quite significant here.
I hope that helps you a bit. It really is a good programme and if you come here, you'll definitely have a good experience if you can rise to the challenge. But you do have to dig yourself out of that GPA hole, so you should consider the most effective way of doing that. Perhaps give serious thought to applying to DO schools, which have grade forgiveness - come to HES and just re-take a number of courses so that you can clear the slate that way...