It depends what you are taking Premarin for. That is, if it is for hot flashes you can expect to take it for a minimum for 2-5 years. There are many ways to get to your health goal. HRT is just one. That's an easy question because there are a number of studies on this.
Lets start with bone density.
So Evista is not a substitute for HRT in an exchange way. Most important, if ovaries are out, is are you getting your fair share of testosterone, the libido hormone. Our ovaries continue to make testosterone after menopause. Absolutely, the BCP would mask the symptoms except during your week on the placebo pills. After 5 or so days on the sugar pills the BCP hormones would be out of your body and you could start having hot flashes.