Magento | PDF Invoice edit

For my supplier i need the following.

When i receive an order my supplier prints my invoice and makes the package ready for shipment.

Problems:
1. I Sell accessories and costumes. On the invoice accessories and costumes are unordered. accessories and costumes are mixed.
2. When there is an item ordered more than once it is very difficult to see. Not very shipment fail proof.

Solution:
Order costumes and accessories on the invoice
if qty of a product is more than 1 > bold and colored background

Costumes and accessories have different atributesets, so i think you can figure something out with that.

I've attached the current invoice, and a photoshoped invoice of what it has to look like.

With the assignment I also want documentation of the code changes. Which code is added in which file, so I know later on what you have done.

I hope you guys can help me.

Greetings
Stefan
Feestding.nl