I am quite sure that they will not count your minor traffic accidents due to your age and hopefully it being a while ago.  The good thing is that you are being honest about it.   

As for the sexual relations question, are you sure you aren't trying to rationalize it or minimize it?  If it happened as you wrote it did, then I am quite sure it isn't prostitution, however, if a price was negotiated  before sexual relations then yes it was prostitution.   If you are being honest then you have nothing to worry about, the thing that makes me a tad suspicious is that on many occasions I am sure we all have taken a female out to dinner/movie/coffe/where ever, and ended up having sexual relations later that night, yet I doubt any of us have ever worried that it might be construed as prostitution.  Yet you somehow equate having consensual sex and then giving her money to help her as prostitution.  Many of us have received sex from a GF or wife and then bought them something the next day.  Is that prostitution to you?

Finally, I am sure that it isn't just a few people keeping the multi billion dollar pornography industry in business.  There is nothing inherently wrong in having seen pornography or purchased it (BECAUSE IT IS LEGAL), however, the exception presents itself when the pornography is illegal.  What they are trully looking for is sexual deviancy, addiction or the signs of a sexual predator, also any involvement with child pornography no matter how you excuse it,  is definitely going to exclude you from any LE job.   

You make a slight reference to drugs and how you are clean, yet don't answer whether or not you used them so I really can't help you there.

please i need the names of the manufacturer of polygraph machine online please.
if necessary now