Is it possible for a creature that has a bite attack but has two poisons for the victim to suffer from both
Ex. Lizardfolk Synthesist with the Serpentine Bloodline Power and Poison Evolution Bites you...Do you take one poison or both and if so do you chose which one goes in what order?
Well, in the Poison Rules it states this:
Unlike other afflictions, multiple doses of the same poison stack. Poisons delivered by injury and contact cannot inflict more than one dose of poison at a time, but inhaled and ingested poisons can inflict multiple doses at once.
So from what I'm seeing only one type of poison effects each attack when using injury/contact poisons. While I admit this probably would be different if you were naturally poisonous, it's the best I have for you.
Yes. The sorcerer power allows you to grow poisonous fangs as a free action, whether you already have a pair or not.
As for the order, I'd say that it doesn't matter, the two fortitude checks should be done before damage is applied, but that's not in the rules.
If both poisons are the exact same type (same Fort save, same duration, same damage, etc.) then the poison has a +2 to the Fort save DC. If the two poisons are different, then they both affect the target, each with their own save and cure conditions.
I believe both RAW and RAI suggest that you would need to use two attacks for two poisons. I suppose the idea is that one pair of fangs has one poison, and another has the different kind. It would need to be two attacks, one with each set of fangs.