Your comments

Well, to delete a file you already have to follow these steps:

- select exactly one file
- tap on the right most button in the toolbar
- tap on the red "delete selected" button

I don't want to display an additional confirmation that you really want to delete this one file.
Sorry, but I don't think I can influence the way UIWebView (essentially an in-app-instance of Safari) displays web pages.
It only asks for permission when you want to delete more than one file.
 I've just tried it on my own ftp server and you are right. I have introduced a bug when implementing SFTP. Textastic didn't correctly check if a file already existed on FTP server.

I have fixed the issue for the next update.

Thank you for reporting this!
Please go to the app's settings and enable the "Read-only" setting. I think this is what you are looking for.

Also, in the next version the keyboard will only come up if you lift your finger from the touch screen without having moved it (instead of after a few milliseconds while the finger is still on the screen but hasn't moved yet). This makes it much harder to accidentally show the keyboard.
Actually, Textastic always checks if a file upload would overwrite remote files before uploading. If not, then this is probably a bug. What kind of remote server are you connecting to for which it doesn't ask for confirmation?
No, that's currently not possible. But it's a good idea.
This will be fixed in Textastic 2.2.