The CDC report you linked to actually distinguishes between homosexual men and men who have sex with men (MSM.) They are not the same thing according to the study. It also stresses the importance of testing and safe sex, it does not indicate one way or the other whether or not homosexuality or homosexual acts in and of themselves constitute higher STI rates. Just that those who engage in such acts appear to be at a higher risk. But that's a correlation at best.
I don't know how many studies the US does on the youth with regards to sexuality. But saying promiscuity occurs among the youth is sort of like saying water is wet. But sure, here you go.
Sexual Behaviors | Adolescent and School Health | CDC
Again it indicates LGBT youth are at higher risk, but I don't know what societal pressures these youth encounters.