There are lots of internet sources for wedding ettiquette. Try Google, Emily Post, The Knot, or About.com
The TTD is a new thing. It is done more at beach weddings, though I have seen others. Visit Trash The Dress
The idea behind it is that you have made a lifelong comittment, will no longer need your dress, so turn it into art.
Rehersal dinners are usually hosted by the groom's parents and it is a chance to celebrate with family and the bridal party and present them with gifts. You do this after you practice the ceremony.
Most people give favors to guests at a wedding. In Jamaica at my wedding, we gave everyone Welcome bags (OOT Bags) only. For the reception back home, we just made a donation to a local animal charity.