Your comments

You can download the Monokai theme from there: http://wiki.macromates.com/Themes/UserSubmittedThemes

The direct link is: http://www.monokai.nl/blog/wp-content/asdev/Monokai.tmTheme

You can then modify the "selection" color in the file. Then you can just add your modified file to Textastic as described in the manual.

I hope this helps.
You can just add a regular HTML style tag to the Markdown file and it will be used in the preview screen.

Something like:

<link rel="stylesheet" href="style.css" type="text/css" />
Usually, SFTP servers already send all hidden files and they are displayed in Textastic. Are you sure they are not displayed?

For FTP, there is a connection setting that you can enable to show hidden files.
With the currently available features no, sorry.
I'm not sure if that's a good idea. In an editor like Word, you can remove the automatically inserted bullet point by tapping a second time. This behavior would need to be added too. 

I fear that many users would not want the app to automatically insert bullet points like that.
I see - I think the selection isn't really adapted to the new word length. I'm actually surprised that no one found this bug so far :)