Classes are relatively small, ranging from 15(seminars) to 70(larger lectures). Since the classes are small, you can get to know your professor, especially if you make use of office hours. For larger classes, there are usually TA sessions, which can be beneficial if you do not undertand the material. I would definitly recommend getting to know your professors because as you go on further into college, and start applying for internships, jobs, grants, scholarships etc. you usually need letters of recommendation from some of your academic professors. If you already have established a relationship with them, its not as awkward asking them for a recommendation.
Barnard is all women, but at least half of the classes are integrated with Columbia guys. The only ones that are all women are the freshman english and some of the upper level seminars, because they are only for Barnard students. And Columbia people are always on Barnard's campus/taking Barnard classes because they are so good. So in no way do we feel excluded from men. After a while its just matter of fact.
Barnard is challenging academically, so alot of time is devoted to homework, papers and tests, especially around midterms and finals. Those times, you do not have a life. Most of your time will be spent in the library, and sleeping sometimes. Since there are so many libraries and study areas between Barnard and Columbia, I advise that you find a few that work for you and then rotate between those during peak study times. That way you can spend 8 or 9 hours studying, but you also get a change of environment, which helps me to stay focused more.
Barnard's requirements are called the nine ways of knowing, I believe. These are the general requirements, plus any other requirements for your specific major. The gen ed requirements were great, because they force you to try out different types of classes. Basically you have to take a year of science with lab, some sort of math or reasoning, freshman english, critical analysis, history, language and gym. Most of the intro level classes satisfy the requirements, so its easy to fufill most of the requirements in the first few years when you are taking the lower level classes. Since two years of language is required, I recommend that you take the placement exam first semester of freshman year to try and place out of some of the language requirement. And if you want to start another language, make sure you start freshman year. I started Spanish, but waited too long, and now I will have to take a year of Spanish my senior year, which just sucks.
In terms of Barnard preparing you for a job, it is definitly geared towards learning for learnings sake. You learn how to be an intellectual, how to question and reason, to problem solve, to succeed, good work ethics, etc. But you do not get any sort of specific training, and most people will need to go on for further schooling or training in the field of their choice. For example, I want to go into buying, and even though my psychology classes have all been interesting, there are no classes at Barnard geared towards entering the fashion industry. I will have to enter a training program after I graduate. Even if I had decided to go into psychology, I still would have to get at least my masters to make any real money. So Barnard is definitly just a stop on the way to getting a job, but what you learn here is so helpful socially...especially in networking in certain social circles, its necessary to have a good edcuational background, especially a liberal arts background where you learn the basics in most subjects.