Ugh. Not good. In my humble opinion people aren't going to scroll down to read that much content - so that's bad from a user experience point of view. So here's some pointers
1. Keep the Home Page Fresh - if they're in the position of being able to regularly add content, then keep the home page fresh, maybe with the latest post and then snippets to the preview 2 or 3 for people who may be interested. Or have an intro page as the home page with a 'latest articles' box that's prominent.
2. Move the other articles to their own page - this means you're growing the site, can better interlink between posts, can optimise each for carefully selected keywords and makes each one individually shareable by social media.
3. Link Build to relevant articles or categories - much more achievable when that content is not on the home page.
The drop-down DIVs are only helpful for users - Google will be seeing 6000 words of text, which is OTT. That content needs moving, so that unique pages of content are created and can be separately promoted.
Hope this helps - a website restructure sounds like it's in order.