I know im late to the party here, but will throw my opinion in anyway. I have only briefly used both Notepad++ and dreamweaver as IDE's and found them both to have issues or characteristics i didnt like. With Dreamweaver I found it was simply trying to do too much, which made it cluttered and clunky at times, for example it tried to appeal to beginners with templates and drag and drop functionality while also branding itself towards professional use by simply being an adobe product and integration with git. In contrast I found Notepad++ to be the complete other end of the spectrum, it feels very minimalist and while it does have lots of addon support and ability to customise for me it certainly felt like a text editor and not an environment I could work in on a daily basis. Its great for portability e.g. A hotfix needs to be implemented and i simply need to jump into FTP grab 1 single file and update it. In this scenario the text formatting is clean and its easy to modify a file, however in long term work I found the lack of a file tree was a major issue.
I know this is outside the reach of your assignment but I have been using Aptana Studio for the past 2-3 years and its done everything I could need, its based on the eclipse platform and comes either as an addon or standalone and is completely free and open source. Sure it has some annoying bugs which when having to use daily used to really annoy me (specifically the git integration can be patchy at the best of times) but on the whole its pretty solid and has done me well.
Hope you do well on your assignment