Importing content to a content type with images and associated data
In Drupal content is store in Databases (SQL) this your text and any link that you inside your content. Images are files that can be call from your content, module or theme.

Tooltips is mainly a front-end work, this is part of the theme or a module. So you do not necessary import from the content from your another framework (or website). You added a module or a theme that support Tooltips.

Here are few modules for Tooltips:


qTip 
BeautyTips
Field Tooltips
Tipsy


You should pick one of these module and you should be good to go.