When Katy Perry weds beau Russell Brand in India this fall, expect plenty of costume changes. A source tells Us Weekly that Perry, 25, will wear at least seven custom-made Zuhair Murad gowns!

In this week's Hot Stuff video, Senior Editor Ian Drew -- plus singer/actress Katharine McPhee! -- reveal more details on the kooky couple's bridal extravaganza, including a very, very famous bridesmaid.

Also in the roundup: Carrie Underwood's Las Vegas bachelorette party, exes Demi Lovato is "talking crap about" ex Joe Jonas, and more.

Watch the video now (above)!