To confirm this, it would be best to consult with your developer(s) as custom coding is out of the scope of Marketo Support.
You may consider using variables before outputting the values so that in the variables, you can ensure that there are no line breaks. For more information, you can refer to http://developers.marketo.com/email-scripting/
2.) If the image is rendering but only for certain browsers and/or email clients, review the coding of the email with your developer(s) as this may be due to the coding of the email itself that may contain code that does not comply with certain browsers and/or email clients.