I agree with most of 2prepmom's points.
About homework: I think the "regulations" are complete and utter BS. Here's why: the main purpose of homework is to help solidify (or in the case of math, TEACH) you the material. Say you're slow to understand a physics concept, or you have a learning disorder, or something; in keeping with the regulations, you put your books away after 50 minutes, with a perfectly legitimate excuse to your teacher if your work is incomplete. What are you going to do on the test if you don't understand what's going on?
If you manage your time properly (which I don't...

), you will be completely fine. Your workload depends entirely on the courses you take and the preparation you have from before.
So, I'm in an accelerated math class. Our teacher told us at the beginning of the year that if we can't keep up with the very fast pace of the class (we cover 2.5 years in one), we should drop to a lower class. I do not want to drop to a lower class, because I love the challenge and, even more so, the feeling that I am living up to my greatest potential (in math, at least). My homework for that class takes me approximately 2 hours a night; sometimes a lot more. I would definitely not wish to trade this class for an easier class that I can reasonably do my homework in less than an hour.
On the other end of the spectrum, I have French class. My previous school prepared me very thoroughly grammatically and such; but I have an obvious deficiency in actual speaking and comprehension. As a result, Harkness French class is the best thing ever; I don't really have to do any of my homework, since I know all the structures, but I'm still learning a ton from being in an environment that is taught entirely in French. If you take a class such as Latin, for example, you may have a sufficiently greater challenge; simply because it is inherently a more difficult course. While the "regulations" assure that you should not be spending more than 50 minutes, some courses will be much more difficult to COMPREHEND than others; inherently making the homework time much longer. History is one such course; the work usually takes me about 90 minutes.
Perhaps the single greatest factor that deters most students from ultimately applying and/or coming to Exeter is the perceivedly great level of intimidation. Some people feel the architecture is somewhat imposing, or that the people aren't sufficiently friendly, or that the workload is simply too much to bear. I have no idea whence this stereoptype arose. Yes, Exeter is an extremely challenging academic environment, but like any institution that puts together (not to mention HOUSES) hundreds of motivated, smart, fun, and nice teenagers together, it's impossible to not have a LIFE.
So, in conclusion: no, you should NOT be worried about being able to manage the course load. On the other hand, you should not fall into the mindset of "hey, that's less than I have now," because, really, the thing that makes Exeter so incredibly AMAZING is the unsurpassed amount of opportunity offered here. This school, perhaps more than any other in the nation, allows a student to live up to his/her full potential. As a result, as a student here you will feel academically satiated and content with yourself.