By the 3rd race I pretty much had the training down so that I could blow all my energy in :30. I was able to average 178 bpm in :33 minutes Is that about right for a cross race? Obviously I didn't have the power yet as I fininshed 3 mins behind the leader at 33/35.

Also my mouth tasted like metal after.

Lap times are what tell you if you are pacing yourself correctly. Try to make a habit of hitting that lap button every time you pass Go.

Heart rate varies substantially from person to person, so averaging X bpm over Y minutes doesn't really say much, without anything to compare.

Sounds right.

https://gritandglimmer.com/pedal-unti...tle-at-barlow/

Yup. When I race, I typically average 165-170 bpm and I'm in my mid-40's. I've spoken to many top riders and they will tell you that cross really pushes your "puke factor". Btw the metallic taste is from breathing hard in the cold - it causes your bronchioles tubes to swell and secrete mucus. No big deal and it's a natural body reaction.