one easy thing regarding 1/4" seame, invest in a 1/4" foot for your sewing machine if you don't have one already. They are made two different ways - both are perfectly accurate it just depends on which machine you have. Here are two pictures PURELY of examples of the two different feet - you will need to purchase the 1/4" foot specifically for your machine.
http://cgi.ebay.com/Janome-Kenmore-H...QQcmdZViewItem
I can't find a picture of the 1/4" foot without the black guide, but they are around - I have one for my janome. Good luck!