This will be available in Textastic 8.

This will be added in Textastic 8 which will be released as a free update for existing users next week.

Currently not, sorry.

You can drag the file icon from the window title bar in Textastic onto the Safari Dock icon to view it in Safari. This also works great with Markdown files when you drag the file icon onto Marked 2's Dock icon.

Not yet, sorry.

Hello,

you can use the "Preview in Safari" feature to open the Markdown in Safari and print it from there. See https://www.textasticapp.com/v7/manual/viewing_editing_files/web_preview.html#preview-in-safari

In Textastic 8 you'll also be able to print the source code with syntax highlighting.

Hello,

revert means that the file contents are reverted to the last time you saved the changes using File -> Save. Also have a look atthe  File -> Revert To menu. I guess that you want to keep the changes you made to the files, so you need to select "Save".

I would recommend to use Cmd-S in regular intervals to save your changes so that you do not get asked this question.

If you just want to save changes and not see this dialog at all, please go to System Preferences -> General and uncheck "Ask to keep changes when closing documents".

(This whole thing is part of the document architecture of macOS and the AutoSave mechanism.)