Welcome to the forum. Thanks for your question.
Escorts (meaning upscale, high-cost sex workers who work by appointment) often are at low risk for most STDs. However, this depends on selecting low risk clients to the best of their ability (e.g., mostly monogamous or married men) and consistent use of condoms for vaginal or anal sex. Oral sex is low risk for most STDs and zero risk for some -- but certainly she is at least at small risk from oral-genital contact with her clients. Low risk also means not having sex with pimps or others who make money off of them. (The biggest STD risk to most commercial sex workers probably comes from their regular boyfriends or pimps, not their customers.) However, your partner sounds like she could be at higher risk than some escorts. Five partners in a day is a lot.
Perhaps most important, the practices you describe are low risk. Fingering, hand-genital contact, and kissing are no risk at all, for practical purposes. As noted above, oral sex would be low risk, but not zero. Condom-protected vaginal sex is zero risk for most STDs (e.g., chlamydia, gonorrhea, HIV), low risk for others (syphilis, herpes), and no risk for chlamydia. There would remain a certain amount of risk for HPV, which probably is quite often transmitted by skin-skin contact above the skin covered by the condom. On the other hand, everybody gets HPV anyway, and you'll be at no greater risk than from any garden-variety sexual partnership, even a committed monogamous one.
In other words, with the sexual practices you plan, your risk for STDs will be low, but not zero. If you proceed, and especially if there are numerous such exposures as time passes, I would advise both you and she to have periodic testing (e.g., every few weeks or months) for STDs and HIV.
I hope this has helped. Best wishes-- HHH, MD