The Knot website provides a ton of useful information pertaining to bridal parties. It would also be worth checking out the Wedding Channel and eHow website.
The Bridal Party was created in 1930.
Many major retailers like Walmart, Target, and KMart carry bridal party gifts at a good price. Specific bridal stores, such as David's Bridal, also carry a selection of bridal party gifts.
Bridal shower is mainly for the bride while the engagement party is mainly for both. Go with a Shower Dance, both sexes can attend :)
Bridal Party - 2008 was released on: USA: 1 November 2008 (Gotham Screen Film Festival)
Bridal Party Massacre - 2011 was released on: USA: 25 August 2011 (Erie, Pennsylvania) (premiere)
One can find tickets to a bridal show online at Bridal Show Tickets. For specific cities, one can go online to Bridal Show Expo, Bridal Bazaar, and Philly Bridal Expos.
Try looking up some places online that sell party supplies at factory direct prices. Once you can compare those prices to those of typical party stores, you can have a better idea of whether or not it would be a good investment or not.
Four Weddings - 2009 I ---And a Bridal Party Band 4-18 was released on: USA: 2012
There are quite a few websites where you can get information on what to give as a bridesmaid gift. I suggest you have a look at this site first - wedding.theknot.com Wedding Planning Bridal Party.
A bridal shower is, indeed, the same as a stagette - also known as a stag party for the bride. Bridal showers, though, have a less raunchy connotation compared to Stagette.
Registering with more than one store leaves options open, so it would be a good idea to do that. If you need more help though: http://www.i-do.com.au/wedding-tips/bridal-registries-bridal-party-gifts/setting-up-a-bridal-registry/1288/
If you are invited to both and you are a close friend (some relatives are friends) it is your choice. If the Maid of Honor has the poor taste to invite the same group to the Bridal Shower and the Bachelorette Party and the above does not apply, it is your call. Personally if the latter were the case, I would not attend.