Dear mtb999
One alternative is to buy the ready made kit from the institute of human potential (Doman's website). The link is as follows:
http://www.gentlerevolution.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=G&Category_Code=bThe basic kit is for USD 50 and they currently have 20% discount off that price. You need to add delivery cost though.
To share with you my view in regards to your questions:
1. I don't think it matters we present the dots in square or rectangular cards. The dots should be placed in a random pattern. In the book of teaching a child to read, Doman said not to be so rigid with the paper size and go with what is available in your location. I suppose same principle, we can be a bit flexible in adopting Doman's method.
The square makes sense though if you want to follow Doman's method to the book, that is teaching quantity, equations everything using flash cards. Square because you write at the back in all four corners number the quantity card represent and lists of equations related to that number. And then you can present the dot card in any directions.
I use A4 though and my baby seems progressing fine with it.
Be careful with the files downloaded. Though we all intend well, we may have made mistakes. I started out downloading a doc file for red dots 1 to 100. When I counted the dots, I had extra 1 dot for nearly the whole set; so I ended up doing my own ppt red dots file from scratch. I will upload it later on if you are interested. One thing though: my dots do not have a black border around them; only reading about it afterwards (not so important for my baby since she was nearly 1 year when I started teaching her).
2. The size of the dots really depends on the age of the child. I assume in your case you will want to teach your newborn baby (because you mentioned that you are on maternity leave). If so the size is important. Introducing a newborn baby to quantity for the first 8-10 weeks is not really teaching him/her quantity but stimulating his/her visual pathway. Doman called it the 'zero step'. He said to use black dots for this time. Posterboard should be 15" x 15" for new born with dots 1 1/2" in diameter or larger if you like. You need very bold black dots on white posterboard to get the appropriate intensity for an infant.
You start with 1 to 7, one dot per day for 10 times. So say Monday is day of one dot card, and you show your baby that one dot card 10 times during the day when he/she is happy. Tuesday is 2 dot card day, and so on. Repeat this process for 3 weeks. Then do the same process for 8 to 14. By the time your baby is 10 weeks, he/she should have a good enough visual pathway to start the so called "1st step" in Doman method.
This is clearly talked in details in Doman's book How to teach you baby math. It would be a good investment. I bought it from amazon.com.
If you have problem buying the book, please tell then I will see if I can scan the appropriate pages for teaching infant and send to you.