I'll go ahead and say that you can't go wrong here. All of the programs that are being discussed are excellent. Even if you're logical, go with your gut- pick the one that feels like an environment in which you'd be successful. Linkages are great, but they aren't everything (this coming from someone who picked a program with the most linkages). Go with the program that's going to give you the best shot at starting this new path. If you're interested, I believe I started a very similar thread to this one when I was debating between Bryn Mawr, Goucher, and Hopkins in the past.
Here's the way my year went:
Spring Session I: Gen Chem, 5 weeks, starting in May. A week of class material covered each day, plus lab. You will be strongly discouraged from trying to volunteer, etc, since you're probably just getting the hang of this science thing.
Spring Session II: Gen Chem II, same as before. This ends, if I remember correctly, so that you get pretty much the entire month of August off, returning right around the 24-27th. Go home and float in a pool for awhile.
Orientation will be the next few days after that, and then classes will start according to a regular college schedule (final exams in early December). I took Orgo I, Orgo I Lab, Physics I, Physics I Lab, Bio I, and Bio I Lab in my first semester. This is echoed in your Spring semester, which starts in January after a hefty break and goes until the beginning of May (just replace each class in my fall schedule with "II" instead of "I"). Pace is slower, but material amount is greater. You'll be more efficient with the sciences and find a rhythm.
How much of a life will you have during your year? It depends. Most people will find that they are working much, much more than they are used to, but the things that are really important in one's life remain. Your work-life balance in any of these programs will depend on the target GPA you're looking for (study more, have fun less, get better results). Some people had multiple priorities that they needed to balance, and their schoolwork was worked into that equation. Personally, I have a zillion hobbies, but I chose to sustain only one or two with regularity during my year (running in particular was a great stress reliever, since the neighborhoods around Bryn Mawr are beautiful). Luckily, my interest in forgotten pastimes hasn't waned since my "year off"
Hope this helps!