I have had my 7700 for about 6 months now and love, love, love it. I even use it on my quilting frame because she's so big!
I have no problem with 1/4" seams. I'm not too impressed with feet that have a blade on them so this is what I do.
I use my walking foot for almost everything, including piecing. I pick a landmark on the foot as my guide. For instance, the outside edge of the right hand rectangular opening. Then I move my needle to the right until my stitch is exactly the scant 1/4" that I want. For me, it's when the stitch width number is 6.0
The blue dot bobbin case is not necessary for FMQ, only if you're going to use "exotic" weights of thread for thread painting etc. The regular case works just fine for most threads that you'd use for piecing or regular quilting.
The screw on the side of the bobbin case is the tension adjustment and is easy to adjust.
Personally, I think once you fall in love with Janome, you'll never go back to another machine.