Traditionally it's the job of the Maid of Honor to host your bridal shower. But more and more these days it can be a sister, or extended/future family. The bridal shower usually happens 1-2 months before the wedding and is usually an afternoon affair. The host of the shower will usually make all the arrangements and ask you for a guest list.
Wording on the invitation can be casual and RSVP information can be written on the invitation with a phone number or email address.
This is also the one time it is acceptable to include the registry information. You can either write it at the bottom of the invitation or have a separate insert card with the registry information on it.
Sample Wording Below....