I'm not sure what you mean. I can successfully clone repositories over SSH with Working Copy.

Did you contact Anders Borum, the author of Working Copy? Usually he is very responsive.

No, it's always binary.

Working Copy is indeed the best option at the moment. You can use the new "Open…" command in Textastic to open and edit files that are stored in Working Copy. You can then commit the changes in Working Copy. You can also use the recent files list in Textastic to open recently used external files.

I'm actively working with the developer of Working Copy to further improve the integration of both apps.

There are also bugs in iOS 8 that I reported to Apple that should be fixed soon to improve the behavior (namely Cocoa Error 256 when opening files using the document picker).

Textastic internally uses libcurl, which uses binary transfer by default.

For now, you can drag the file icon from Textastic's window title bar onto the Safari Dock icon to view it. 

The Mac version does not have FTP functionality at the moment.

Yes, that would be possible to implement, but isn't yet available in the current version of Textastic.

You need to create a folder called "#Textastic" (with a capital "T"!) in Local Files yourself.

You can find more info with screenshots in the manual at http://www.textasticapp.com/v5/manual/lessons/How_can_I_add_my_own_syntax_definitions__themes_and_templates.html

In general, the auto-correct feature in iOS does not work with hardware keyboards, but only works with the virtual on-screen keyboard. You can try this in any other app like Apple's Pages or the iOS Notes app.