May diarrea and headache sign something after 9 days?
Golly, you have an interesting life! I can't imagine being offered a ******** in my local Waterstones in a thousand years!
You are not at risk of HIV.
As to the "exact" chances of catching the diseases you've identified, thats an impossible question. I think also that since you allowed yourself to be sucked off in a bookshop the other guy might reasonably think you were promiscuous as well, so I'm not sure your thoughts about him are that reasonable.
You can test for gonorrhoea and chlamydia at 5 to 7 days after the event using PCR technology. You can test for syphilis at 28 days using an IgG and IgM test at 28 days along with if you are still worried, an HIV DUO test at 28 days (although as I say, I don't believe you need this).
Herpes is more difficult. If you have lesions then a PCR swab will identify it. You can also diagnose it using a PCR urine test. You can have a blood test for herpes but this tends not to be reliable until 12 weeks post event or two samples with the second showing a rise in antibody level. Your local clinic etc will be able to advise about that.
I think you should stop looking at the internet and for symptoms and just wait for the intervals I've described and then get tested to put all this behind you.
Go to a different bookshop in future!!
best wishes, Sean