We engaged in the typical massage with some light touching, followed by protected oral in which she sprayed my penis and the condom alcohol.

Following that we engaged in protected vaginal sex. After combing through some of the posts here I have seen multiple times where the doctors say that most CSW do not have STDs/STIs. 

With that being said when we were engaged in covered vaginal sex upon ejaculation, I inserted my penis deeply into her vagina therefore, resulting in the part of my penis (the base), that was not fully covered by the condom, touching her vagina/genitals. Also, my pubis area was firmly pressed against her genitalia as well (this contact took place while in the doggy style position) It was for a short amount of time but there was contact, without question. 

The base of my penis touched her vagina for a short amount of time following me ejaculating she took the condom off and sprayed my penis once again with alcohol. 

Upon returning home, I showered and vigorously washed my penis with soap. The duration between contact and showering was less than 15 minutes. 

My questions are as follows - 

1-being that the base of my penis was not covered by the condom and touched her vagina. What is the likelihood of contracting a lesion based STD? 

2- if a lesion-based STD is of concern at what point time wise, am I in the clear… three days, five days, etc. 

2a-what time frame should I be looking for lesions and or abnormalities?

3-does the alcohol spray play any sort of part in preventing the spread of STDs?

4-what should I be on the lookout for?

 As you have already indicated you are risk from the encounter you described is virtually zero. As you also mentioned, most commercial sex workers do not have STI‘s and even when they do most single unprotected sexual encounters do not result in infection. In your case Condoms were used, making your risk even lower. Contact of the base of your penis and penis shaft near the base with her genital secretions is no risk in terms of risk for HIV, gonorrhea, or chlamydia. There is a theoretical risk of acquiring a lesion, STI, such as syphilis or herpes, but that risk as well is also very very low. Thus, an answer to your specific questions.