In my experience, Dreamweaver is the most comfortable WYSIWYG software that can be used to design as well as edit code for websites or applications. Yes it has few basic Flash buttons that you can instantly use. But to get more interactive or high-end animations you may have to use Flash itself. You can then embed Flash files (swf files) into webpages using Dreamweaver. Frontpage is something I used long time back, but somehow it didn't give me that much motivation to explore creativity! You can surely use it as a practice-tool though and then move to higher end packages!
As for playing around with purchased templates, it depends on how the template was created. If it is html, you can used Dreamweaver. If it is the flash content that you need to manupulate, then you need Flash!! For the kind of presentation items you have mentioned, if you are looking for colorful still images, you may create using Photoshop or if you are planning for animations, best is using Flash!
Flash and Dreamweaver are Macromedia products & Photoshop is Adobe product. Check their websites to procure Trial versions to see if this is what you are looking for!
Hope this was helpful!