i'm not reading all of this so i apologize if i'm repeating anything. but generally, i think the rule is that if it's above the neck (i.e. head cold), you're fine, but if it's more than that, you need to rest. and while it's ok to ride with a cold, you should take it easy and back off or stop if you feel worse.

i usually find that i feel better during/after exercise when i have a cold...YMMV.