Obstacles:
http://usdaa.com/rulesReg_ObsReqs.cfm
http://nadac.com/equipment_specs.htm
Official obstacle requirements can vary from organization to organization so you'll have to pick and choose which ones you want to use for your english project.

Scoring:
http://usdaa.com/rulesReg_ScoringMeths.cfm

Training Tips:
http://www.dogpatch.org/agility/FAQs/