what are the competition ID and competition Class? are these things in some document somewhere?

IGC Sporting Code 3 para 6.5
http://www.fai.org/igc-documents select "Sporting Code Section 3 - Edition 2014"

is there an authoritative source for the log Interval?

IGC Sporting Code 3 Annex C para 6.6
http://www.fai.org/igc-documents select "Annex C"