How did you enter the special characters in the HTML? Are they entered as & #2713; (✓) and & #2113; (ℓ)? I've never used these two characters so I don't know if they are even supported in the Kindle device's font.
As far as TOC problems, it seems to me as though the method you are using to create a book is very convoluted, and it involves at least one inferior product for developing HTML. MS Word is terrible at developing HTML. You might want to learn about Sigil, a freeware app for developing ePubs. It has a WYSIWYG editor to create HTML, allows you to easily create and organize a book. Once Sigil creates the ePub it is very easy to unpack/unzip the ePub and modify the OPF and NCX files. Then you can easily use Kindle Previewer to open the OPF and build a MOBI. This is much easier and much cleaner than using MS Word and MobiCreator.