Your comments

It's a common mistake to include more than just the host name or ip address, so that's why I mentioned it. It's easy to add a trailing slash when you are copying it from an URL for example, so that happens quite often. No offense meant.
Regarding WebDAV: you can upload files using WebDAV to your webserver. In the preview screen of Textastic you can switch to "Remote" and enter a remote URL that is served by your webserver. Textastic itself does not run PHP code locally.
Can you send me a screenshot of your FTP connection settings? Make sure that you only put the IP address in the "Host" field - do no't include "ftp://" or a trailing slash.

You can find detailed information in the manual at http://www.textasticapp.com/v5/manual/lessons/How_do_I_connect_to_an_FTP__FTPS_or_SFTP_server.html
Thank you very much! I really appreciate it.
How exactly do you try to bring up the keyboard? Please make sure that you are doing just a single tap, not a double-tap and not a long press gesture.
Update 2015-04-17: The latest versions of Textastic have the Fountain syntax definition built-in. The default themes are intended for programming languages, so you can still install and use the themes from http://www.textasticapp.com/support/FountainThemes.zip to make full use of it.

A customer also requested support for custom colors for synopses, actions and dialogue. I modified his theme and added styles for it. You can download this theme here: http://www.textasticapp.com/support/Highland.tmTheme.zip

Here's a screenshot of this theme:




You can use the theme editor at https://tmtheme-editor.herokuapp.com to modify colors (the editor requires the desktop Chrome browser).
It's great to hear that it works now!