Hi Mish - I know how excited you must be because just last Thursday (a little early) I got a Janome 300e Embroidery machine. It has less bells and whistles than yours does but an acquaintence that I know who does lots of quilting and has lots of machines was selling one at a good price and I just had to have it.
I'm having lots of fun with it but have LOTS of questions. I do know that it is .JEF format on the patterns.
I bought some embroidery thread at Joann's that day with some 40% off coupons but I'm not using that yet. I'm using up old thread - have a lot of that - that I wouldn't trust using in any quilting projects. One "old" spool actually had the price on it - believe it or not - it was 19 cents - LOL. I think it had to be my grandmothers - and I'm 70 - ha ha.
One of my many questions is how do I do pictures on small pieces of fabric - pieces that are too small for a hoop? Maybe if you don't know someone on here will answer.
My machine came with the adapter but no card. I ordered a card online at a good price. So far I am just using the patterns that are built into the machine but I have downloaded some that I will be able to put on the card when I get it - probably at the end of the week.
Keep in touch - maybe we can learn together.
Pat