It is my opinion that the amount and type of "benefit" from circ related to these STDs varies widely across studies, and that often, researchers pick and choose the examples they want to use to show the benefit they prefer. So I tend to view these claims as suspect, and potentially erroneous.
In order to know about these particular claims, you would need to see the actual, scientific article and its references. I would be interested in doing this, but I don't have time right now :)
However, the bigger question is this: does male circumcision ERADICATE the risk of these/any STDs? Absolutely NOT. It might lessen the risk of some sorts of transmissions, but it might also increase the risk of others (thinking male to male, male to female, and female to male; then considering each individual virus or disease ... you can see it's a complicated matrix). In truth, even if the "best" risk reductions are accurate (which I doubt they are), transmission occurs to and from circ'd partners too. Your son having been circ'd will NOT eliminate his risk of acquiring or transmitting ANY sexually transmitted disease, period. This is unlike the case in favor of some vaccines, which DO effectively eliminate your child's risk of acquiring a particular disease (but vaccines are a totally different issue, and I'll not sidetrack this thread onto that topic).
Circumcision is not preventative for STDs. Abstinence, being faithful, and using condoms -- those are the only ways to truly decrease your son's risk of acquiring or transmitting any STD. Period.
In some cases, I believe that those who promote circ for STD prevention do a big disservice -- some circ'd men (and their partners) believe that their risk is less than it truly is. In other words, they feel that the circ was analagous to, say, a polio vaccine. Unfortunately, this is totally, completely wrong, and when they then fail to use condoms consistently/effectively, they transmit STDs.
Anecdotally, in the US, ask any woman you know who has HPV about the status of her infecting partner -- I'm betting 80% or more were circ'd. So much for "eliminating" risk. Also anecdotally ... look at STD rates in the US in the 1980s and 1990s, when our circ rates were the highest on the planet other than, maybe, Israel ... and guess what, our STD rates were also sky-high. STDs are an issue of behavior and education, not amputation.
Regarding HPV specifically, I believe that all children 9-12 years old will eventually be offered Guardisil (or its equivalent) as a two-stage vaccine. Probably by the time my eldest is 10, which isn't that long. I know that parents feel differently about vaccines, and I"m not here to promote them per se, but if HPV is a significant concern for you, you may have your child (boy OR girl) vaccinated at the appropriate time. Again, amputation of foreskin is not the least-invasive, most-appropriate option -- prevention is.
Finally, no matter what we may or may not learn about STD transmission in the next 20 years, your INFANT SON receives no benefit from being circ'd. Even if he is sexually precocious, I figure you have at least 10-12 years before this is in any way even a topic of discussion.
Someone else here will be better able to address your individual STD questions, I'm sure. HTH!