Nina, congratulations on your new machine. I have the lesser model of Janome the 423S but I love the machine, it is well made and it does what I need it to do. Here is a website where I brought all the extra feet I wanted, including a walking foot, and a darning foot for free-form quilting. Neither of these came with the machine. The site is reasonably priced too.
http://www.sewingmachinesplus.com/?g...FdFL5Qodsho6hQ
Try Connecting Threads for you thread. They are a much better quality then Coats & Clark and they also are reasonably priced, $1.99 for a 1200 yard spool and $7.99 for a 5000 yard cone.
http://www.connectingthreads.com/Quilting.cfm