Both of these are based on the editor module example in the documentation for commenting lines (http://omz-software.com/pythonista/docs/ios/editor.html). I was finding it hard to move code blocks around or remove lines with only white space, so I wrote these up and put them in my action menu.
Select Line - https://gist.github.com/4048131 Selects the line that the cursor is currently on. If multiple lines are already selected it will select to the start of the first line and end of the last line in the current selection. Once one line is selected you can easily add lines to the selection.
Other idea of two finger ... In an LaTeX editor, one can move the cusor with two fingers left an right as well as up and down In pythonista, placing the cursor at exacly a letter inside a word seems to be not possible? Therefor this post
You can slide with one finger across the extended keyboard rows to move the cursor in Pythonista (not up and down currently, but placing the cursor inside a word shouldn't be a problem).