Font compatibility is definitely an issue to be carefully considered, I would agree, yet there is another issue concerning the use of multiple fonts that is overlooked by people who did not get on someone's bad side when designing a web page or any other design for that matter! (obviously i have!) It was only then that i took the time to research the matter of fonts.

Typography is quite a field and design with type is one fascinating field, i personally think the most difficult in design!

However, we usually tend to use different fonts to create this effect of diversity or something else, but the more fonts you use the less enjoyable it will be!

If you want to use more than one font use 2. One for the major info and one for the details, in all the pages!

Personally however i would agree with Peter that the use of one font is best, and then just play around with it by changing to italic, bold and/or size is much better!