I advise being friends first with any potential significant other
i think people are more guarded and more likely to lie if they feel like they are on a job interview with someone they are trying to impress and that person is asking them hard hitting questions like
“have you ever cheated”
“have you ever blah blah blah ...”
they will just tell you what you want to hear.
get to know them on a friend level first if possible and maybe those questions will be answered through just general conversation when both of you are more relax.