I understand that completing the I-129f is a bit stressful. My advise is to not overthink things, too much.
On the USCIS website, there is an instruction PDF. Just follow what it says. (I found many website from Visa-assistance companies and Immigration lawyers that had very incorrect information). If you follow the instructions, you will meet all of the requirements and you will avoid overdoing anything.
I put passport photos in a ziplock bag and paperclipped it in my packet.