In most features the editor is using a full set of toolbar items, it is only limited in use by untrusted users like in the forum or blog comments, though if logged in as admin you get the full toolbar in those features too.
The full toolbar has a style dropdown which has "Document Block" as an option, this is a div.
Im ASP.NET, you can only have 1 form in a page so you do not want users to be able to add extra forms in the editor as this will cause postback errors and unexpected results.
I'm working on a FormWizard feature that will be available for sale soon to make it easy to add arbitrary forms to a site for collecting submissions of any kind from your visitors.
Hope it helps,