There is no reason at all why AnthroAIs need to have great strength. It's established that they can transfer their electronic "selves" into any chassis they require, and do so when required; the humanoid firm is just one particular version for a specific function. So, by Occam's Razor, they are no stronger than humans and probably much less strong.
Likewise, Pintsize's online "date" with another AI shows how AI "sex" actually functions. It's an electronic exchange. Pintsize is notionally "male" because the plot requires "his" character to be exaggeratedly laddish; Winslow is asexual because that's a plot point, too. The Idoru sales staff are "female" because of Pintsize's anecdote, but mostly because the scenario requires a characterisation as being apparently educated and trustworthy, but in a fairly low-level job and this doesn't work so well with a "male" avatar. Chibi-Momo is apparently, Marigold's choice of chassis with Momo's personality, while Momo-as-now is Momo's choice of chassis.
Holographic May is a joke about Dale, in the same vein as the "green skinned space babe" joke in Grrl Power. I strongly suspect that May-as-now will prove to have been allocated to Dale as part of her parole, because she needs to develop her socialisation and Dale is in a fairly short list of people who she can, or will relate to. Dale obviously signed up for the glasses trial without reading the small print, or even most if the quite large print, after all, so he doesn't understand the situation.
So, robo-sex is an off-colour but in-character joke by Pintsize. Momo's Sven-fantasy is a projection of her actual function, interpreted in humanoid firm because she us in a humanoid body. Any of the AIs could have an analogous relationship with any of the others, as Pintsize did, because as the little guy demonstrated, the whole issue of their nominal sexuality isn't an essential part of their identity.
Really, it comes down to perceiving them as "people". Momo et al aren't human. This is why Momo has re-acquired the visible joint around her neck; to remind readers that she ISN'T the young girl she superficially resembles.