I wrote a post to refute the Federal Vision misinterpretation of these verses here. It deals with Jn 15:1-3 pretty heavily, then hits the highlights up through Jn 15:8. Although I wrote it for a different purpose, the exegesis may be profitable for your inquiry as I believe that it answers both of your questions.

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Bob Mattes
Ruling Elder, Christ Church of Arlington (PCA), Arlington, VA
Reformed Musings Blog

"All that is necessary for evil to succeed is that good men do nothing." - Edmund Burke
"We old folks have to find our cushions and pillows in our tankards. Strong beer is the milk of the old." -Martin Luther