Textastic 2.1 will honour the system setting for keyboard sounds.

Also have a look at this feedback entry: http://feedback.textasticapp.com/feedback/7730-remote-source-code-compilation/

You can preview HTML with CSS and JavaScript using the builtin preview feature.

Apple doesn't allow execution of user-supplied code on iOS devices, so I can't add this feature for languages like C# oder VB.

Sounds like you're not using Textastic 2.0 yet. This version requires iOS 4 though.

So your problems should be fixed when you update to Textastic 2.0: there it's possible to create files that start with a dot (like ".htaccess").

If the problem is that you cannot access hidden files on an FTP server (like .htaccess): there will be an option for that in the next update.

What exactly is not working for you?

Can you please send me those files to support(at)textasticapp.com so I can try to reproduce the crash?

Well, you can simply choose the lisp syntax highlighter in the File Information popover and keep the file extension. Textastic remembers the chosen syntax definition for the next time you open the file.