Seeing that I knew some escorts, I can assist here
1. I would STRONGLY recommend NOT going down on any of them. You have no clue where those Vageen have been.
2. Yes, many of them charge more for anal. Figure out the codes you have to ask for, or they advertise for, if they are up for anal. "Greek" will be their code.
3. Again, if she is going to blow you, and let your random load into her mouth, do you really want to make out with said mouth, after she has taken hundreds of random loads in there? I mean, its tempting to want to do some of those things, but you have to get a good read on them to make sure they are taking care of themselves. Are they really clean, are they getting tested frequently? Hard to tell. I'd stick to doing stuff where you dont have a chance of getting any of her fluids in you, to be safe. Some of those women are seriously, and dangerously crazy.
what area of the US do you live in? See if you can find women on Eros, Preferred 411 or Roomservice 2000. If you are going to seriously "dabble" as a "Hobbyist", you may want to pay the $50 at RS2K (Roomservice 2000) and get verified, so the gals dont think you are a cop. Backpage is going to get you some shady gals. The other 3 have better classes of women and far less chance of getting busted.