To the naked eye, it Contains 83 stars. The brigthest are the northern and southern claws. :)
The 4 brightest stars are: α Librae, Zubenelgenubi ("southern claw"), a visual binary; β Librae, Zubeneschamali ("northern claw"); γ Librae, Zubenelakrab ("scorpion's claw"); σ Librae, Brachium,...
The number of stars in Preseus is: "6". But you will get some debate on what stars are included, you said stars in Perseus, answer 6.
Hundreds. See related link for a list
I think two.