What are the statistical chances of catching various STDs after unprotected sex? Also do you know of any studies I could read regarding this question?
The best data is found at www.cdc.gov but approaching it from the standpoint of "what are my chances of getting ______ infection after this unprotected (or protected) encounter" is not a very helpful way to evaluate your odds. You are suggesting using the "odds" to help you decide whether the gamble is worth it or not. Not wise.
That's analogous to a health care worker saying "what are the chances of me getting infected with Hepatitis C or HIV from not wearing gloves with this patient whose history I don't know if they come in bleeding". The risks are probably low but not ever zero. So health care workers use universal precautions for all patients, every time, every touch. That is exactly how sexual partners should think of potential body fluid exposures. Protection, every time, every touch--yet acknowledging that even with protection, the risk is never zero.