Hello,
I already code a solution for this for my previous employee.
I used a solution based on some open source plugin c# : ITextSharp or includes word processor dll
1. Needs to be html 3.2 compatable
For your doctype no problem to open html and change it before display it i think
2. Have .jpg images and not .png images
Images url can be changed with regular expressions, and i can code a converter png to jpeg
3. Correct font from PDF needs to be used.
Natively , itextsharp permits to get the font used by pdf, a code can be used to change the html encoded
4. Download a zip file that contains the images and html file in one folder.
I used the library .net ionic to create zip file, Easy
The real question is : What about your budget? How urgent this app is? If it's for make sell maybe we can discuss about a interest and not cash payment?
Regards,