First off, you should change
python:"<img src='%s/view/++widget++form.widgets.screenshot/@@download' />" % item.getObject().absolute_url()
to:
python:"<img src='%s/view/++widget++form.widgets.screenshot/@@download' />" % item.getURL()
Since this way means you don't have to get the full object. Note the use of the getURL()
method.
For the second expression, try something like this:
item/getObject/@@text-transform/body
or
python: item.getObject().restrictedTraverse('@@text-transform/body')
untested