Your concerns are important and you may need to ask him these questions to try to find out what kind of person he is. Don’t hesitate to ask difficult questions because this is an important decision. You will need to feel satisfied with him and he needs to show that he regrets what he’s done and has changed.
Ask him for examples of how he’s dealt with a similar situations after repenting, and what he would do if he was tempted in future. Don’t rush into it and take your time (obviously while keeping everything halal).
Don’t marry this person (or anyone) based on his potential. Marry a suitor based on who he is now. If you don’t feel satisfied, walk away with the belief that inshaaAllah Allah will replace him with someone better.