I've actually asked the UserEcho guys. They say they are going to implement the missing features asap: http://feedback.userecho.com/topic/84539-which-features-to-add-for-polls-first/

Ok, it seems like you can only vote for one option and can't change it after you voted. That kinda sucks, because I want to be able to select more than one preferred language.

It would probably have to include all languages that are listed here: http://www.textasticapp.com/v4/manual/lessons/Which_file_types_are_supported.html

I just added a poll to this topic by using the "more..." link on the top right of the post. I don't know if only I can do that or if you can do it too.

Not yet. I have released the JSON files for customizing templates and code completion at https://github.com/blach/Textastic-Customization/

Version 4.0.1 with high resolution graphics optimized for the Retina display on the new iPad is currently waiting for review at Apple. Here's a full-size screenshot: http://www.textasticapp.com/images/textastic_retina.png

It's explained in the manual:

Please keep the ideas coming! I appreciate any feedback. However, there might be restrictions on the iOS platform that I cannot work around.

Added in Textastic 4.0.