When you import a file, your document is kept as it has been uploaded. If you want to download it to verify, you can use the link under the Content / Main file part.
About the preview we provide, the PRE is generated on our side: we want to be sure this upload will not break a specific formatting. In your case, if your files looks like articles, either you have to prepare your NotePad files to have a limited character size by line, or you have to keep the way it is displayed now.
In the last version of Nuxeo Platform (5.5+), i've improved the presentation, you have now a scrollbar for each text in PRE.
Your text is contained within a pre or code html tag. You can see it with the font used. These tags are used to display text exactly as you typed it. It preserves spaces, line breaks, carriage returns, when you want to show code lines for example.
Since you want to have a paragraph result, you can format your text with a paragraph p tag.
- about PRE tag: http://www.w3.org/TR/html4/struct/text.html#h-9.3.4
- about the CODE phrase element : http://www.w3.org/TR/html4/struct/text.html#h-9.2.1