Well, from what I've read online, what you've said so far seems pretty accurate. I am planning to switch to a biphasic schedule starting... today actually. However, I do have one question--does it make a difference whether you get your core sleep first or last? In other words, are there arguments for or against taking the ninety-minute nap first, staying up, and then going to sleep for good, versus doing core sleep, getting up, and then taking the nap?
I think the main argument for taking the nap first is that the core sleep would theoretically leave you more refreshed for the next day. The ninety minutes would be fueling only about 4 or 4.5 hours of awakeness, whereas the 4-hour core nap would be fueling eight or more hours.