Here are some devotional sites that are helpful:
http://www.jesse-trees.com/parent/parent-devotions.html - parent devotions
I purchased my twleve day devotional set from Illuminated Ink. The ornaments that we used were ones that my kids took turns coloring and cutting out. They ended up being three dimensional and the kids loved them. They were so excited when I pulled them out again this year.
Here are a few sites about making the Jesse Tree:
http://www.kingofpeace.org/resources/ - Scroll down for ornament templates
https://www.pcusa.org/advent/pdf/advent-eng1.pdf - printable ornaments with instructions
I hope your kids have as much fun as mine are having!