Just do a single tap on the code editor to make the keyboard appear. You can then select text by double-tapping.

If you do a double tap instead when the keyboard is not shown yet, you only select the word under your finger. This allows you to select text and copy it to the clipboard without bringing up the keyboard.

Yes, this is planned for a future update.

Hello, you can tell Textastic to wrap lines at column 80 in settings: disable "Auto Word Wrap" and then you can enter 80 as the value for "Wrap Column".

Please note that this is soft wrap - it does not insert new line characters into the file.

Emmet extensions are not supported in Textastic for iOS at the moment, sorry.

It's great to hear that it worked out!

Thanks for letting me know. I'll try to reproduce it.

Textastic can open and highlight .tex files just fine.

How are you trying to open the file? In case you are trying to open it using the Open… command and Google Drive:

This is a problem when opening files from Google Drive using the "Open…" command in Textastic. This invokes the iOS document picker and uses the Google Drive file provider extension of the Google Drive app. Unfortunately, the Google Drive app has some bugs.  

Instead, please use the remote transfer screen of Textastic: tap on the "globe" button in Textastic and create a new Google Drive connection. You can then download and upload files using this connection. It also allows you to download whole directory trees.  

It's basically the same functionality as for Dropbox, which is explained here:  
https://www.textasticapp.com/v6/manual/lessons/How_do_I_access_files_in_my_Dropbox_account.html

Can you please send me an example file that crashes the app when using that bundle?