Nice work. Though, is the first issue a real issue? Markdown is often not friendly with HTML tags in general and to have expected result, one should leave a blank space between the tags and other markdown parts.
It often depends on the markdown flavour and the tools probably but in my opinion, people just did not learn to use it properly. On the other hand, Steemit and even Busy changes the behaviour with every report. For example, if the images were not displayed without <img> or ![](), I believe that it would be much better.
RE: Markdown-It Plugins: Proxy Image & Mixed HTML Fixer