Under the additional settings tab within your credit control settings, you'll have the option to add your company logo and email footer and enable late fee calculation for late payers. Once you have uploaded your company logo, this can be added to your email templates by using the company logo snippet within your email templates. The email footer will be automatically added to the bottom of your automated emails.
Ticking the late fees box will enable calculation of late fees on each overdue invoice. You'll then have the option to add this information to your reminder emails by using the 'late fees' snippet within your email templates.