Is Jabba compatible sexually with humanoid women. Could he get Leia pregnant. If not why does he have girls in scantily costumes?
The hutt species in the Star Wars is hermaphroditic meaning that
they have both male and female sex organs. Hutt's usually choose
what gender role to take when they reach adulthood, but this can
always change with preference. Jabba himself, as many hutts in
power usually do, took on the male persona and thus has a male
labido and sex organ. Jabba has only once taken a femal persona and
that was when he became pregnant with Rotta. Hutts change gender
once they become pregnant.
As far as compatibility is concerned, while it may be possible
for Jabba or another male persona hutt to have sex with a female of
another species that does not mean he can impregnate them. While
Jabba might enter Leia and ejaculate inside her, his sperm would
not be able to impregnate her, do to the differences in the human
and hutt species. Creatures can only reproduce with other creatures
with a similar amount of chromosomes. That is why it is impossible
for a human to impregnate another species.
So now to answer your last question about why Jabba has a sexual
attraction to other species if he can not ultimately make children
with them. It is a similar reason why some humans find themselves
attracted to humans of the same gender or creatures of another
species. They can't reproduce but they still are attracted to them
just like Jabba is sexually attracted to humaoid females. It is
even stated in several books that Jabba's harem is considered a
perversion by other hutts and only Jabba's wealth and power keeps
him from ridicule.