If someone ingests a contact or injury poison, do they suffer the affects of the poison?
Ingestion poisons usually have an onset and longer frequencies, if yes on the first question does the onset/frequency of the contact/injury poison ingested change?
I don't know the RAW answer, but from a practical standpoint I would say that ingesting a contact poison causes the effects - it IS coming into contact with you, against soft tissue no less! It will also likely get on your lips if it's in a drink. Ergo, eating contact poison should poison you. If the poison is baked into something, or added before/during cooking, that may differ - cooking would likely break it down.
Injury poison, on the other hand, needs to enter the bloodstream to be effective. The human (and presumably humanoid) digestive system will likely break down an injury poison well before it can reach your blood (unless you have open sores in your mouth or an ulcer). Perhaps if you add it to the dip for some doritos or corn chips, the eater might stab their mouth with a broken chip, but it seems like low odds to me.
These are, of course, based upon the real world. What happens in the real world may not be accurate to the rules of the game.